Ken Takayanagi, universally called Ken-chan, shares a childhood bond with Azusa Noyama (Azuki-chan). His family runs a ramen stall adjacent to her apartment complex, resulting in constant interaction as Azuki habitually orders noodles from them.

He exhibits a teasing attitude toward Azuki, especially concerning her unpopular nickname, yet conceals unrequited romantic feelings for her. This affection strains their dynamic and creates friction with Kaoru Nishino, one of Azuki’s close friends, who secretly pines for Ken. While initially indifferent toward Kaoru, Ken slowly warms to her as their connection deepens.

Ken forges a pivotal friendship with Yuunosuke Ogasawara following his transfer into their class. Alongside Makoto Sakaguchi, they become central figures in Yuunosuke’s social group. Ken’s loyalty and protectiveness manifest when defending Yuunosuke from bullying by senior students, underscoring his supportive presence.

His family life involves a father managing the ramen stall, who appears sporadically. Ken’s mother is infrequently portrayed. The character remains confined to the main series, absent from any spin-offs, OVAs, or films.