Mushoku Tensei: Isekai Ittara Honki Dasu

Synopsis

Philip thanks Rudeus for protecting Eris and warns him to not reveal to anyone his connections with the Greyrat family or he may be targeted again. Later on, Ghislaine teaches swordsmanship to Eris and Rudeus, while Rudeus teaches magic, literacy and math to both. However, Eris usually skips classes out of boredom and Rudeus decides to give her one day off per week to encourage her. While taking a stroll in the city, Eris attempts to buy Rudeus an expensive book, but he refuses, claiming that she cannot give presents to others without her own money and suggests her father to give her an allowance. With her allowance, Eris presents Rudeus with a vial he was previously interested in, which puts him in a pinch, as he is in fear of revealing to her and Ghilsaine that it is in fact an aphrodisiac.

(Source: Wiki)