I appreciate you reading and your critique Mota. :) Yeah, I didn't see Marisa choosing violence unless something went really wrong, but there were other ways things could go poorly. Fortunately everything seems okay. :) So now we get to figure out Danmaku. Oscar sadly won't be able to participate much, even if some of his stage tricks might be useful. I once mused if he were a boss in the games, he wouldn't actually do damage. Just modify the battle while his minions fought you. He might warp your screen, shoot rockets to buffet you around, or even open your options menu to change the brightness. He'll probably follow a similar idea, blinding or deafening people. At least until he can get 'real' spell cards. Even then, probably won't be a real threat with them unless you outwit your foes.
I'm glad you and Mokou-tan enjoyed the disguises! I'll be honest, I hate the Human Village. Part of the reason is, for a place called the Human Village, there aren't many humans there. Sure, there are humans in the side stories. But I don't think the game's had a fight there with a 'true' human. Even on the Wiki, most of the characters listed living in the town are Youkai. Keine, Kogasa, Sekibanki. Sure, Marisa technically has a shop there, but she's transitioning into a youkai/devil. Same with Kosuzu. Even Akyuu is debatable. While scenes of the Bakette as schoolmates is cute, the lore both tells us that non-humans aren't welcome in the village, but they also come and go as they please. This is my compromise between the world-as-written, and the world-as-imagined. Cirno and friends attend the school at night, disguised as humans when no one will spot them. They're only outside now because they woke up and noticed their new friend wasn't eaten alive by hungry trees. :P
Not quite. :) He shares inventory with Agappa, who plundered eight bullets off a body earlier. They're useless as weapons without their firearm, but a creative person might find a use for their components. Even if the idea of a spell card just being 'gun' is amusing.
I dunno. I always thought of Marisa as a good person, even if she's a thief. Oscar would have to convince her he was a real piece of work for her to Master Spark all over the place. But there are many ways he could ruin his new life in Gensokyo outside 'spell card to the face', and Marisa could do that in several ways. As for why she hasn't stolen anything, I think that's more down to him not having anything to interest her, outside the other grimoire. And that'll be easier to steal now that he has two of them.
Ah yes, the Shrine Maiden in the room. If you can get Oscar on Marisa's good side, she may be able to protect him just a little from her. Its less 'I will die for this handsome stranger' and more 'I'll call my best friend a jerk for being so rude to a new friend'. Not that it'll do more than make Reimu temporarily argue with Marisa. Reimu may not like Oscar much, though we will see why as time moves on.