Summer Wars (2009): FUll Synopsis & Analysis – Explained to the End with Character Map and Family Tree (Spoilers)

Summer Wars(Official) is a feature-length animated film directed by Mamoru Hosoda, released on August 1, 2009. The box office revenue was 1.65 billion yen (Reference: “Motion Picture Producers Association of Japan ‘2009 National Movie Statistics'”, in Japanese).

The story begins when the protagonist, Kenji Koiso, who is good at math but a bit timid, takes on a “part-time job playing the boyfriend” of his beautiful senior, Natsuki Shinohara. It is quite a convenient beginning, and for me, who was a student at the time of its release, it was an embarrassing enough start (though it was fun even back then).

However, when viewed as the story of Wabisuke and Grandma Sakae, it is a film that cannot be watched without tears, and it remains a work I love even now that I have become an old man.

In this article, I would like to consider the analysis points while looking back at the synopsis of Summer Wars. What kind of work was this movie?

*Since I will tell the entire story in the “synopsis” below, if you dislike spoilers, please read only halfway and watch the main feature.

Summer Wars (2009) Synopsis (Spoilers)

Summary of Synopsis Points

Detailed Synopsis

The Dream Part-Time Job

The protagonist of the story is Kenji Koiso, a 17-year-old high school junior. Kenji, who has math skills capable of aiming for… the Math Olympiad Japanese representative team, was doing a part-time job maintaining and inspecting the internet virtual space OZ with his friend Takashi Sakuma (at the very, very, very bottom end).

At that time, he nonchalantly follows his admired senior Natsuki (Natsuki Shinohara) for a new “part-time job” she was recruiting for: “going to my parents’ home together.” He visits the head family, the Jinnouchi family, in Ueda City, Nagano Prefecture, to attend the 90th birthday celebration of Natsuki’s great-grandmother, Sakae Jinnouchi.

Kenji visits the Jinnouchi family and greets Grandma Sakae with Natsuki, but there he is introduced as her “boyfriend and fiancé.”

Natsuki had heard that Grandma Sakae was not feeling well lately and thought that bringing a boyfriend might cheer her up, so she executed this operation.

Kenji had to keep up the lie for at least the four days until the birthday was over, but the setting Natsuki prepared was that of a high-spec boyfriend as follows:

While Kenji is bewildered by the setting that is the exact opposite of himself, the people of the Jinnouchi family gather one after another.

Kenji was introduced as the “fiancé” at a banquet where more than 10 members of the Jinnouchi family gathered for Grandma Sakae’s birthday. Although bewildered by the situation, he was generally welcomed warmly. The only person who viewed Kenji with hostility was Shota, a police officer and Natsuki’s childhood friend (Shota is Natsuki’s second cousin).

Even Grandma Sakae, who had only spoken to him a little, seemed to like Kenji very much.

The Man Named Wabisuke

As the night deepens, the atmosphere of the house changes completely with the arrival of a single man.

The visitor is Wabisuke. He is the illegitimate child of Grandma Sakae’s husband, Tokuei Jinnouchi (who married into the family), and was adopted by Sakae in his childhood (blood-wise, he is Natsuki’s grandfather’s generation, but age-wise, he is in Natsuki’s parents’ generation). He had run off with the Jinnouchi family’s assets and had been missing for 10 years.

While the members of the Jinnouchi family were hostile toward Wabisuke, only Natsuki was happy about his arrival. Wabisuke was Natsuki’s first love, and the specs of “Todai student,” “from an old family,” and “studied in America” that she set for Kenji were all based on Wabisuke.

Natsuki enjoys playing “Hanafuda,” which she was taught by her beloved Uncle Wabisuke and Grandma Sakae. Kenji was desperate to learn the rules while watching the two play. And Kenji was no longer reflected in Natsuki’s eyes.

As Kenji goes to bed with complex feelings, he receives a mysterious email with the subject “Solve me.”

The email contained a string of numbers, and Kenji, who took on the challenge of decoding it, brilliantly arrived at the answer and replied to the email.

When dawn broke, someone had intruded into the OZ system, bringing it down, and many accounts were hijacked. Then, Kenji’s photo was broadcast on TV as the culprit. Kenji tried to log in to OZ immediately, but his account had also been stolen by someone.

Suspect Kenji Koiso

Kenji, who had become a suspect in the OZ system failure, receives contact from Sakuma. According to Sakuma, someone had breached the OZ system protected by a 2056-digit encryption, and that was exactly the code Kenji had solved the night before.

While the account situation does not recover, the situation becomes slightly clearer. According to Sakuma, the culprit of the incident is a hacking AI called “Love Machine,” which seems to have “escaped” from a robotics institute in Pittsburgh.

At that time, the TV broadcast is discovered by the Jinnouchi family, and the lie Natsuki and Kenji told is exposed in broad daylight. Furthermore, Kenji is temporarily arrested by Shota, the police officer.

The impact of the OZ system failure gradually increases, and confusion spreads throughout the world.

In the face of the worsening situation, Grandma Sakae makes phone calls to the Jinnouchi family members working hard and acquaintances in important positions to encourage and scold them in order to calm the confusion.

OZ’s systems engineers were also responding to the situation but could not enter the OZ administration building. Kenji took on the challenge of decoding the encryption that was the barrier and succeeded. The OZ system was gradually restored, and the confusion subsided.

According to OZ’s security log, there were 55 people in the world who solved the 2056-digit code, but Kenji was not among them. He had mistaken the last character of the code.

Although it was slightly regrettable, Kenji’s suspicion was cleared.

On the other hand, the cause of this OZ system failure was deemed “accidental occurrence of identical accounts,” and the truth was to be hidden. Even so, 2 million OZ accounts remained unusable.

The Truth of the Incident

On the night when the OZ system failure reached a temporary lull, Wabisuke appeared again at the banquet where everyone was comforting each other after overcoming the confusion, and revealed a shocking fact.

It was Wabisuke who developed “Love Machine,” the cause of the confusion, and this disturbance was a demonstration experiment using OZ by the US military, which had taken an interest in “Love Machine.”

Wabisuke took the stance that he was merely the developer and had not given instructions like this to the AI, but the Jinnouchi family members who were actually dealing with the commotion blamed him severely.

However, Wabisuke was undaunted by such things and proudly told Grandma Sakae the following:

To Wabisuke, who thought she would accept him, Grandma Sakae showed an extreme rejection reaction and pressed Wabisuke, saying, “Die here!”

Disappointed by Grandma Sakae’s figure, Wabisuke left the Jinnouchi family, saying, “I shouldn’t have come back.” Kenji cared for Natsuki, who was shaken by the sudden event, but there was nothing he could do for her at the moment.

Grandma Sakae, who called such Kenji to her room, suddenly told him while playing Hanafuda with him, “If I win, please take care of Natsuki.” However, Kenji, who had no confidence in his own existence, could only respond, “I’ll try.”

The next morning, a great tragedy occurs.

The Death of Sakae Jinnouchi

At 5:21 AM, Sakae Jinnouchi passed away. She had originally suffered from angina, but in the opinion of Mansaku Jinnouchi (Natsuki’s great-uncle), who is a doctor, it was “old age.”

The Jinnouchi house had lost a great presence and felt like the fire had gone out, but the women, centered on Grandma Sakae’s eldest daughter, Mariko Jinnouchi (Natsuki’s great-aunt), began preparing for the wake and funeral.

On the other hand, Grandma Sakae’s second son, Mansuke Jinnouchi (Natsuki’s great-uncle), insisted on revenge against “Love Machine,” and Kenji responded to that. However, their insistence was brushed aside by the women.

Even so, while preparations for Grandma Sakae’s funeral were steadily progressing, Kenji and the others secretly formulated a revenge strategy against “Love Machine.”

Revenge

The key person in the strategy Kenji and the others planned was Kazuma (13 years old, Natsuki’s second cousin). He was famous in OZ as “King Kazma” and was a master of combat in OZ.

They planned a strategy to challenge “Love Machine” to a one-on-one combat match and use that battle as a decoy to seal “Love Machine” away.

To that end, Tasuke Jinnouchi (Natsuki’s uncle), who runs an electronics store in town, borrowed a supercomputer scheduled for delivery to a university; Riichi Jinnouchi (Natsuki’s uncle), a Ground Self-Defense Force officer, borrowed a powerful module for internet lines from the garrison; and Mansaku brought his own boat from Niigata to serve as the power source to support them.

Proceeding with preparations that would be impossible under normal circumstances, they almost succeeded in sealing “Love Machine,” but… suddenly the supercomputer went into thermal runaway.

The supercomputer was being cooled by placing large blocks of ice, but Shota, who knew nothing of the operation, had taken them out to cool Grandma Sakae’s body.

As a result, not only did the operation fail, but the situation worsened.

“Love Machine” used the stolen accounts to seize control of the asteroid probe “Arawashi,” which was returning to Earth. It executed a plan to crash “Arawashi” into nuclear facilities around the world. The remaining time was merely two hours.

The Final Battle

While the members of the Jinnouchi family despaired at the situation, only Kenji did not give up and explored possibilities. Meanwhile, Natsuki succeeded in contacting Wabisuke, whose whereabouts were unknown, and conveyed the news of Grandma Sakae’s death.

Wabisuke, who returned to the Jinnouchi family immediately, paid his respects to Grandma Sakae’s remains and proposed the remote “dismantling” of “Love Machine.” In parallel with that, to retrieve the more than 400 million stolen accounts, Natsuki challenges “Love Machine” to a Hanafuda match. The stakes were the accounts of the Jinnouchi family members.

As the Hanafuda match continued back and forth, she was caught off guard and put in a predicament, but people all over the world offered their accounts to cooperate with Natsuki, succeeding in liberating almost all accounts.

However, “Love Machine” held on to the account with GPS management authority for “Arawashi” and plotted to drop it on the Jinnouchi family.

Kenji uses his calculation skills to send fake correction information to the GPS atomic clock, attempting to shift its activation even slightly, but meets resistance from “Love Machine.”

With one minute remaining until the crash of “Arawashi,” with the cooperation of Wabisuke and King Kazma, they succeeded in correcting the orbit. Although they received significant damage, the people of the Jinnouchi family were all safe…

After the incident, Wabisuke came forward as the developer of “Love Machine,” and it also came to light that it was the US Department of Defense that released “Love Machine” into OZ.

Meanwhile, at the Jinnouchi family, Grandma Sakae’s birthday celebration cum funeral was being held.

Watched over by many people, Kenji and Natsuki harmoniously welcome their new days.

Main Characters, Character Map, and Family Tree

Introduction of Main Characters

Character Map

Family Tree

You can see a more detailed family tree by clicking “Family Tree” from the window that opens by clicking “Characters” from the sidebar of the “Summer Wars” official website, in Japanese.

Explanation of the Story (Setting and Virtual World OZ)

The setting of the story is the Jinnouchi family, Natsuki’s mother’s parents’ home in Ueda City, Nagano Prefecture(Official), in Japanese. They used to have large assets, but due to the dissipation of Natsuki’s great-grandfather, they do not boast that much glory now (although they possess a very large mansion). Nevertheless, thanks to the efforts of Sakae, Natsuki’s great-grandmother, they continue to be a distinguished family boasting various deep connections.

Also, the scene of the incident involving the world was the virtual space OZ, which has the following characteristics:

This virtual space OZ ends up being overrun by the AI “Love Machine” developed by Wabisuke, but the beginning of it lies in 55 people around the world solving a 2056-digit code by hand.

I am very sorry to say this, but at this point, OZ’s security cannot be called the world’s highest level at all, and it is reasonable to think that it would have been impossible for it to become such an infrastructure before the incident caused by “Love Machine” occurred.

However, what I want to explain here is not “that’s why Summer Wars is bad,” but that the virtual space and decryption were merely tools to drive the story forward. Although it looks like near-future SF at first glance, it should rather be called near-future fantasy.

Personally, I like the movie Summer Wars very much, but people who are concerned about the substantial looseness of OZ’s security might not be able to accept this movie.

On the other hand, for people like me who can think, “Well… isn’t that fine!“, since the essence becomes “Kenji Koiso’s growth” and the “family story,” I think they can come to like this movie.

Well, I understand the feeling of seeking sci-fi precision, but if you can hold back on that for Summer Wars, I think you can enjoy the work.

Analysis of Summer Wars (2009)

The Kindness of Shota Jinnouchi, the Man Who Almost Became a War Criminal

In the main film, Kenji and the others win the battle against “Love Machine,” and structurally there is no “war criminal” in that battle. However, there is a man who was one step away from becoming a “war criminal.”

That person is Shota Jinnouchi, Natsuki’s second cousin who works as a police officer.

He took out the ice prepared to cool the supercomputer for revenge against “Love Machine” without permission, causing the failure of the operation. In the development of the story, someone needed to play the “fool,” and one could view Shota as the victim of that, but I am probably not the only one who felt anger towards him at first sight.

How should I put it? There is a huge “something” that is normally impossible right there, and for some reason, a massive amount of ice is surrounding it, so it is only logical to verify the situation by presuming that “someone is creating this situation for something.” His action is annoying in that it led the operation to failure, but more than anything, his arbitrary judgment is annoying.

However, on the other hand, it is not impossible to defend his actions.

After Grandma Sakae’s death, the women were busy preparing for the funeral and wake, and the men were diligently working on revenge against “Love Machine.” I think everyone had deep love for Sakae Jinnouchi in their hearts, but Grandma Sakae’s remains were lying alone in solitude in the middle of the midsummer day.

Seeing such a figure of Grandma Sakae, Shota probably couldn’t sit still and thought he would make Grandma cool.

While the people of the Jinnouchi family were busy with “preparations for the funeral and wake” and “revenge against ‘Love Machine’,” one could argue that only Shota showed the kindness of thinking about Grandma Sakae’s remains themselves.

Everyone was mourning Grandma Sakae’s death in their own way, and Shota was one of them.

But, let’s strictly refrain from moving things someone has set up without permission. Such a guy deserves to be punched.

Why Does “Love Machine” Like Games?

“Love Machine” threw OZ into chaos, but a major reason why some response was still possible was that “‘Love Machine’ likes games.”

This is the root of the reason why it answered King Kazma’s challenge letter and accepted the Hanafuda showdown with Natsuki.

According to Wabisuke, “curiosity and thirst for knowledge” were given to “Love Machine.” It is natural to think that “Love Machine’s” love for games also stems from that, but… can’t we make a slightly different deduction?

In other words, I think we can also think that “Love Machine” likes games because Grandma Sakae liked Hanafuda.

In the first place, the development of “Love Machine” progressed because there was support for Wabisuke, and during that development, he must have always been thinking about Grandma Sakae.

And above all, Wabisuke might have been playing Hanafuda with “Love Machine” to test its performance. Because he was testing performance with the game of memories taught by Grandma Sakae, “Love Machine” consequently became a game lover.

Since there is absolutely no basis for this way of thinking, it is not something called “analysis,” but if you think this way, you might be able to feel something heartwarming about the nature of “Love Machine” being a game lover.

Does Wabisuke Have Responsibility for the Incident?

Wabisuke is the developer of “Love Machine,” but does he have “responsibility” for the series of incidents?

In the main story, Wabisuke defended himself saying he was just an AI developer and did not instruct the disturbance, but the Jinnouchi family members did not accept it at all.

Personally, I want to support Wabisuke’s claim.

Of course, I understand the feelings of the Jinnouchi family members, who worked in fire services and such, wanting to blame him. However, if you blame him, you should blame the development of science and technology itself.

This judgment depends on individual personalities, and since there is no absolute standard, I think there are objections.

However, isn’t the biggest problem what happens after the story? Wabisuke came forward as the developer of “Love Machine,” and it also came to light that it was the US Department of Defense that conducted the demonstration experiment.

He is truly the “man of the hour,” and a peaceful life will probably not return. Since there are various people in the world, many people who blame him severely will likely appear.

Since he will receive “social sanctions” in that form, shouldn’t at least we forgive him?

Why Did Grandma Sakae Support Wabisuke?

This conclusion might seem to contradict the figure of Grandma Sakae as the absolute head of the Jinnouchi family and that overwhelming leadership she showed during the chaos of OZ at first glance.

Why did she continue to support Wabisuke, who (allegedly) ran off with the clan’s assets, keeping it a secret from the family? And how does that action connect with the strength she showed as the head of the “family”?

The following article digs deeper into the true meaning hidden in that famous “phone call scene” and the “other life” Grandma Sakae entrusted to Wabisuke.

What do you all think?