Kaito is a NPC behind & next to the Nichirin Swordsmith, Jako.
Kaito will change your Nichirin Blade color for 3,000 Yen or 50 Robux.
Colors are for cosmetic use only, and do not provide buffs. If you want to get one of the colors you like, you can talk to Kaito to change the Nichirin Color. You can only have one color on the sword at a time.