Akio, Wataru's friend in Tokyo, was Mami's older brother. The two are initially seen to have a bad relationship, with Akio treating his sister more as an agent than as a sibling and her caring little for him. Akio accuses Mami of having grown decadent on Promised Island, whereas she finds his intentions for Wataru to be distasteful. Later, they seem to be growing a little closer to each other, Mami managing to playfully tease Akio and him reminiscing a little about their past together; apparently she used to address her brother with the nickname she has bestowed on Wataru, 'An-chan'. Yamada is the third ferry passenger who goes with Wataru and Mami to Promised Island so he would enroll at the school there. As soon as he finds out about Wataru's many sisters, he becomes very envious of Wataru. Yamada then proceeds to be more positive and outgoing towards Wataru shortly after, specifically whenever he is around his sisters in order to get closer to them. But eventually, he does begin to consider Wataru as a real friend and Wataru himself meets up with Yamada on the school roof occasionally to ask for advice. Ironically, at one point, Wataru offered to switch places with Yamada due to still being freaked out about his current living situation. Yamada, believing that Wataru is stating arbitrary facts about how much better his place was than his, refuses pessimistically. At this time, he did not know of Wataru's sisters. However, he never once looked back on this decision again after later finding out about them, hinting that he simply forgot about the proposition altogether. Akio is Wataru's best friend back in Tokyo and the recipient of Wataru's e-mails which the latter writes at the beginning and end of almost every episode. He has plans to have himself, Wataru, and another friend, Minai, to go to the same high school together and eventually become the elite men in society. But this plan fails after Wataru's failure in the entrance exam. The continuation of his plan is the reason why he sent his little sister Mami to watch over Wataru. At the end of the anime, Akio is jarred from his own vision of the future by Wataru's refusal to stay in Tokyo. He follows Wataru to Promised Island in the company of Mami and enrolls there, according to him in an effort to find