Wabisuke Jinnouchi

41 years old. The illegitimate child of Tokue Jinnouchi, who was a son-in-law. He was taken in by the Jinnouchi family during his childhood and became Sakae's adopted son. Although he is the much younger brother of Natsuki and Kazuma's grandfathers and the fourth son, he is of the same generation as Sakae's grandchildren.

He disappeared for 10 years after absconding with the family's assets but suddenly returned when the relatives gathered to celebrate Sakae's birthday. A wanderer, yet possessing a genius intellect. He graduated from the University of Tokyo and has studied abroad. In America, he worked as a professor at Carnegie Mellon University, researching secure programming, block and crack, and artificial intelligence, and developed the automatic cracking AI program "Love Machine." Selling this Love Machine to the U.S. Department of Defense triggered the series of events in the story.

Due to his words, attitude, and past behavior, he is disliked by the family, but he secretly admires his foster parent Sakae and treats Natsuki, who admires him, kindly. When questioned about the series of events by Kunihiko and others, he nonchalantly told the family, "I'm just the creator of Love Machine, I didn't give it any orders." He further angered them by showing Sakae a formal offer from the U.S. Department of Defense, saying, "This will bring more money into this house than in grandpa's time, so I can repay grandma," and "Thanks to grandma's money, I was able to develop Love Machine independently." He brushed aside the naginata blade Sakae thrust at him with his hand and said, "I shouldn't have come back," before taking Shota's car and leaving the house.

Later, while wandering aimlessly, he learned of Sakae's death from Natsuki, who contacted him via an overseas line after cracking his smartphone password (Sakae's birthday in English notation, 0108), and hurried back to help Kenji and the Jinnouchi family stop Love Machine.

He was Natsuki's first love, and the fake background used when introducing Kenji to the family was his. Among the Jinnouchi family, he was the only one using an iPhone, which had just been released at the time, while the rest used feature phones. Outside the Jinnouchi family, Sakuma also used a smartphone resembling an iPhone.

In the end, he turned himself in to the American authorities and exposed the cause of the series of incidents. A CNN anchor reported on this, saying, "However, he is merely the developer. The Department of Defense, which conducted the experiment in a public setting, cannot escape responsibility."

The character was designed by Sadamoto based on a young Juzo Itami, following Hosoda's intention to "perfectly characterize Juzo Itami."