Umineko no Naku Koro ni Doujin Fighter – Ougon Musou Kyoku

Just recently this game got announced, all we have so far is a trailer and some screens, but it looks like it's a tag-based game. I can also confirm double jumping, since if you look very closely in the tiny screens when the video pans around, you can catch it.

You can also see counter hit messages in the screenshots.