Natsuki Shinohara (篠原 夏希Shinohara Natsuki?) - A popular 18-year-old high school student and a close friend of Kenji Koiso. She invites Kenji to meet her large extended family for her great-grandmother Sakae Jinnouchi's 90th birthday. She originally invited him because she had promised her great-grandmother to bring her a boyfriend/fiancé. This was because she was frantic, thinking Sakae was going to die and made a mindless promise. Her uncle Wabiskue shows up and the household falls apart. Her grandmother wanted him to leave, but Natsuki wants him to stay.
However, her fake boyfriend Kenji gets framed for destroying the Oz security system and turning the world into chaos, the family finds out soon enough and arrests him. When he returns Nataski says nothing but welcomes him back. Her grandmother dies soon after his return, due to Oz being down and not notifying them of her medical treatment. Natsuki calls Wabisuke to come home, but he refuses until after she tells him that Sakae is dead, then he comes home instantly.
Natsuki uses her Oz avatar to challenge Love Machine to a game of Koi-Koi and wins, taking back all of the stolen Oz avatars. But after they win, the satellite that was orbiting earth is commanded to crash into their house by Love Machine. Kenji stops it just in time and readjusts its course, making it crash not far from their home and saving them.
Natsuki in the end actually falls in love with him and kisses Kenji on the cheek, during their dead grandmother's 90th birthday party/funeral at their damaged home.