Born in Kumamoto, Japan, toi8 is an illustrator for magazines and light novels. He graduated from a Senmon Gakkou for Anime and joined Studio 4°C afterwards. His penname comes from his birthday, which is the 8th of October (literally 'the tenth month' in Japanese, being 'to' one of the readings for the ideogram meaning '10').

He is married to fellow illustrator/designer, Ozaki Tomomi. They worked together on the anime TV series Le Chevalier D'Eon.