Natsuno lives and attends school in Sotoba. He hates living in the village and prefers to be in the city. Originally a city dweller, Natsuno reluctantly moves to Sotoba with his parents when they wanted a change of environment. He often exhibits a cold exterior, especially disliking Megumi Shimizu's presence, who has a crush on him and is obsessed(to the point where she stalks him). He is kind and friendly toward those whom he considers his friends (Tooru, Kaori, Akira and Tooru's younger siblings) Natsuno is one of the two main protagonists in the series.

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His best friend Tooru is forced to turn him into a shiki. However, unlike the normal shikis who cannot go out in daylight and can be killed in various ways, Natsuno is the very rare "werewolf" type of vampire like Tatsumi, who can stand the sunlight and cannot be killed. As a shiki, Natsuno avoids drinking human blood, which makes him weaker than Tatsumi, and allies himself with Toshio to bring down the Kirishiki family even though Tooru remains by Sunako's side. It is also shown that he still deeply cares about Kaori and Akira. At the end of the anime series, Natsuno tackles Tatsumi and they both fall into a deep pit of dead bodies. Detonating the top of the pit with a stick of dynamite, Natsuno buries himself and Tatsumi beneath the rubble.