Perhaps headcanons idk

Please just give it a chance okay

Reiji would be fascinated at Masa's calligraphy skills and he enjoys to teach Reiji about them. Most of the time he doesn't fully listen or the info doesn't quite sink in but Masato envies his determination and effort.

Masa loves watching Reiji cooking and can never get his head around what makes his chicken taste so good. Every so often they would cook together and Reiji will try to incorporate his signature chicken where possible. Even after his endless efforts to try and tell him how to cook his chicken, Reiji never shares his secrets.

Reiji loves to tease Masato as he gets flustered easily but he also has a habit of accidentally annoying him instead.