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.

Sosuke Kaburaya is a detective struggling to make ends meet. While on a case, he happens upon Sara da Odin, a princess from another world who wields magical powers. Sara quickly adjusts to modern Japanese life as Livia de Udis, a knight from Sara's kingdom, arrives to find her. Soon enough, both Sara and Livia's positivity begins to rub off on Sosuke and the neighborhood's cast of characters.

When a gamer is summoned into another world by two girls who accidentally enslave themselves to him, the trio departs on a journey to undo their bond.