The self-proclaimed "old friend" of Nozomu Itoshiki, who, like Nozomu, likes old things. It is later found out that they weren't old friends but rather "one day friends" in elementary school. His name is a reference to the anime series Ikkyū-san. He attempted to marry Rin, thus gaining an "old name" and becoming a member of an "old family", but Kafuka thwarted him in his advances.