Jigoku Kisetsukan is kinda like a cheap offbrand Touhou Project game, but more. It has the whole "unlock each playable character by meeting them in the story mode and complete the game as all of them to unlock the final story" system from Sonic Adventure. The first playable character replaces the rest of the playable characters as a boss in their respective stories. Each playable character has a different shot type with its own shift focus mode behavior, a different bomb type however negligible those differences may be, and a unique final boss designed around the PC's strengths and shortcomings. Each stage can be practiced as each character, and single stage high scores are recorded in addition to full playthrough high scores I believe. As is par for the course, a full playthrough attempt on easy mode will still steamroll casuals in the end. The game is free on Steam and Itch I think.