Ryuuou no Oshigoto! (The Ryuos Work Is Never Done)

Ryuuou no Oshigoto! is a story about a teenage boy named Yaichi Kuzuryu who happens to be the strongest shogi player in history, holding the top title of "Ryuo" (Dragon King). One fateful day, shogi-loving elementary student, Ai Hinatsuru, appears before him claiming that he promised to be her master. But was such a promise really ever made? Thus began their master and disciple relationship!

(Source: BookWalker Global, edited)