Ryuu Shindo

He's a happy-go-lucky guy who is Kazuma's best friend as well as his neighbor. He is also Teppei's kindergarten teacher and is one of the few people who know about Kazuma and Fumino's marriage. He helps to take care of Teppei. He also tells Fumino about Kazuma's past. In one chapter, Ryū shows Fumino a picture of Kazuma and himself back in high school. Kazuma's face looks dark and demonic in the picture and he had long hair with insane demonic eyes. He added that Kazuma beat up the cameraman after taking the picture. Ryū also helps Fumino dress sexy for Kazuma. How he managed to have women's lingerie is a mystery but it was revealed that he previously worked as a host in a club. (Source: Wikipedia)