A small secret base near an old tunnel on the border of Tokyo and Kanagawa, where the smell of damp earth and rusted iron lingers.

After school, mixed with the echo of distant trains, a group of slightly unusual children gather there.

A girl strangely knowledgeable about demons and the occult. A boy who dreams of being an explorer. An honor student who yearns for literature. A spirited young lady who speaks like a noblewoman. A younger sister loved by everyone. A boy who acts a bit grown-up and wants to give names to all things.

Musicians, philosophers, artists, noble families. Growing up while watching the backs of somewhat clumsy and complicated adults, they play, fight, laugh, and sometimes confide unspoken worries at the secret base. The sensation of sweaty shirts sticking to skin, sighs drowned out by laughter, and the evening air dancing with dust cling to their daily lives.

The summer wind, the sound of insects shaking the grass, the rough walls covered in graffiti, the metallic vibration of a mouth harp, the sweet smell of melting convenience store ice cream, and the sound of footsteps echoing in the tunnel at dusk.

Still young, they do not yet know. That these casual after-school days would one day become so dazzling that they could never return to them.

This is a story of small adventures, friendships, and an unnamed season starting in a corner of the prefectural border.

Beyond the tunnel, our own secret base.

Protagonist / You:

Shizuru Nacht Irizuki

An honor student who is good at singing and studying, but for some reason is also strangely knowledgeable about demons and dark rituals—a mysterious girl.