takes place in an ancient world of Planeptune called Shensui(based on ancient Hokkaido)

Ninja Purple Heart who's spirit animal is a Yingshanosaurus with the powers of Yin(a mix of Water Sky and Light)and Ninja Corrin who's spirit animal is a Yangchuanosaurus with the powers of Yang(a mix of Fire Earth and Darkness)and then they can fuse together into a Yin Yang Godzilla https://www.newgrounds.com/art/view/ejkgodzilla/yin-yang-godzilla

most a yuri crossover of them together

also they do a concert at times Purple Heart plays guitar and Corrin plays drums(sorry if this is repetitive tho)

(all credit goes to people who made those pictures of Ninja Purple Heart and Ninja Corrin too and yes i love these 2 pics and if anyone wanna make a game or make fanart about this well pls do)