谜之青年

只有跟某個角色關係變得親密時才會出現的謎之青年 。性格天真爛漫 、爽朗、無憂無慮 。 住在哪？在做甚麼 ？是甚麼人 ？這些全都是謎 。

简介来自 Bangumi

Only when he sees that you're close to a certain somebody in the story, will Nazo no Seinen make an appearance. He is naive, innocent and cheerful with a bright and carefree personality. Where he lives, what he does and his identity is a mystery. [Taken from the official website]

简介来自 VNDB