The World's Finest Assassin Gets Reincarnated in Another World as an Aristocrat (2021)

S1E3 Magic of Bonds

Lugh's magic instructor is an attractive young woman named Dia. A few years his senior, she looks after him like a younger sibling and often sneaks into his bed at night to cuddle. Lugh, reliant on her guidance to learn magic, doesn’t mind the arrangement. As time passes, the bond between him and Dia deepens, bringing them even closer together.