Looking kinda Mahoro in that second panel there, Koakuma. This is a really cute little comic, the oddness of -100 year old humans aside.
This may be obvious, but the "Akumite Beam" thing is a Dragon Ball reference - Akkuman's signature attack. It amplifies the dark thoughts in the target to the point their heart explodes, but it doesn't have any effect if the target doesn't have any negative thoughts (which is why Reimu hastily bluffs that it wouldn't work on her anyway since she's a good girl.)
Also: I just noticed Marisa has a slime on her card, pbbft.
Past Marisa saying 「ぜ」? I can't read this anymore.
I think I'm in love...This has nothing to do with you, Koakuma!!I don't make deals with devils!Hey, you two.Please don't bully Lady Patchouli.I'll give you chocolates...Bad girl!!Halflings stay out of this!I'll use my Akumite Beam on you!!Hmph!! We'll let you off easy this time!!I'm a good girl so the Akumite Beam wouldn't work on me but I'm letting you off easy anyway!!It's all right now, Lady Patchouli.That devil lady is so pretty...Koa, Koa!*blush*