Older twin brother of 666 Satan mangaka Kishimoto Seishi.
His twin brother Seishi Kishimoto is also a mangaka and the creator of 666 Satan. Their art has been remarked as being very similar and accusations of plagiarism were made, either that Seishi had copied his brother or vice versa. However, Seishi notes in one of the volumes of his manga that the similarities are not intentional and that the occurrence would have been likely because they have been influenced by many of the same things. After several accusations, Masashi Kishimoto has asked that fans stop calling his brother a "copy-cat".
Itakura Yuuichi was his assistant.
Married in 2003 and has children.