Kamen no Ninja Hanamaru was released on March 16, 1990 in Japan for 5800 Yen.
Hanamaru shares a striking resemblance with Akakage (aka Red Shadow), a popular Japanese ninja who also wears a similar red mask. The character was originally created by Mitsuteru Yokoyama in 1967 (better known for his works Tetsujin 28-go or Giant Robo), and was featured in several manga, anime and movies (the ninja also starred in its own Famicom game called "Kamen no Ninja - Akakage
" and published by Toei Animation in 1988!). Fortunate coincidence or incidental inspiration ?