In a flooded world, a boy rescues a robotic girl from the sea. Grateful, she vows to be his "leg" until fulfilling her former master's order, leading to an unforgettable summer adventure.

In this anime adaptation, an overworked 24-year-old finally decides to live a little and create a bucket list, when a zombie outbreak hits the country.

Otaku Asahi is transported to another world, expecting powers but finds he's ordinary. His sister Maya appears with actual abilities. They seek a way home while Maya protects Asahi from an approaching Demon King's army.