Once the greatest hitman of all, Taro Sakamoto retired in the name of love. But when his past catches up, he must fight to protect his beloved family.

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.

Stars are everything, granting abilities to Tamers. So when Ivy was born without one, her village took it as an ill omen.