From Renta!:

Kaito has started working part-time at Masayuki, a chocolate shop named after its renowned owner, Masayuki Hanazono. Kaito's actually a spy for a competitor and is after the maestro's notebook, which is said to be full of secrets behind his popular chocolates.
Though Kaito can't stand the man at first, he's dazzled by his craftsmanship. Meanwhile, Masayuki seems to take his interest the wrong way, and one thing leads to another!
This is an eat-or-be-eaten story about a battle of love between a chocolatier and his apprentice!