Antagonist of Summer Wars. AI contracted by the U.S. for &quot;testing&quot;. His thirst for knowledge drives him towards hacking OZ after being released by the U.S.     Love Machine insatiable thirst for competition is his only weakness.

When timid eleventh-grader and math genius Kenji Koiso is asked by older student and secret crush Natsuki to come with her to her family's Nagano home for a summer job, he agrees without hesitation. 
Natsuki's family, the Jinnouchi clan, dates back to the Muromachi era (1336 to 1573), and they've all come together to celebrate the 90th birthday of the spunky matriarch of the family, Sakae. That&rsquo;s when Kenji discovers his "summer job" is to pretend to be Natsuki's fiance and dance with her at the birthday celebration. 
As Kenji attempts to keep up with Natsuki's act around her family, he receives a strange math problem on his cell phone which, being a math genius, he can't resist solving. As it turns out, the solution to the mysterious equation causes Oz, the program that controls nearly every aspect of life to be hacked into, it's up to Kenji and his new "family" to stop the hacker before it's too late. 
(Source: twitchfilm.net)

Cousin of [Marina Massironi](https://anilist.co/staff/157944)

Kenji Koiso is a high school student with a crush on a kendo club beauty, Natsuki Shinohara, and a knack for mathematics. His aptitude with numbers earns him a part-time working maintenance on the global virtual reality world, OZ. 
 
One day, right before summer vacation, Natsuki asks Kenji to do her a favor -accompany her to her great-grandmother's 90th birthday celebration deep in the Japanese countryside. As Kenji tries to find his footing amongst the boisterous and tightly-knit Jinnouchi clan, receives a mysterious email with a long code and the message: "Solve me." Little does Kenji know what solving that code could lead to...
 
(Source: Kodansha USA)