Because Rein was a weak and simple beast tamer, he was expelled from the hero's group but that didn't stop his desire to be an adventurer. By taking simple quests afterwards he has a destined encounter with a strong cat girl.
Asahi Rintarou is a 2nd year high school boy who called out his senpai Shiori to a park in order to confess his love. As he readies to convey his feelings he realizes that they are not alone in the park and that someone was right behind them the whole time.