As should be obvious, she is the mother of Ryuunosuke. She is mostly unseen during the course of the series.
Ryuunosuke's Mother first met her husband while they worked at an amusement park, as actors in a superhero stunt show. They fell in love, and quickly married. After Ryuunosuke was born, she either disappeared or died (either is possible), leaving Ryuunosuke to be raised solely by her father.
Because of her husband's efforts in trying to forget her, a lot of information about Ryuunosuke's mother is missing, down to what she looks like.
- The name Masako means "real, genuine" (真) (ma), "sand, grit" (砂) (sa) and "child" (子) (ko).
- Masako's surname Fujinami means "wisteria" (藤) (fuji) and "wave, breaker" (波) (nami).