Gensokyo/Curio Trader

The Curio Trader is an NPC vendor that can spawn once the following conditions have been met:
 * There is an empty House.
 * At least one player in the game world has a Point Item in their inventory, or any Boss has been defeated.

If the Curio Trader is killed, he will only respawn if the conditions are met again.

When attacked, the Curio Trader will defend himself with the Kusanagi. He may also drop it on death.

Quotes
Always:
 * "I've never seen some of these creatures before... are they cryptids?"
 * "Somehow it feels weird not being the only male around."
 * "Is this the Outside World? It's different than I imagined it."
 * "I hope someone is taking care of Laika while I'm here. I promised that she'd never be lonely..."
 * "I like to tailor clothes that remind me of home. In the right place and time, I can remember what their clothes look like exactly..."

Daytime:
 * "I know a couple of women who would like to get some shots of this place."
 * "While I'm glad about the lack of youkai, the slimes somehow are even more annoying."
 * "Does this place have any crested ibises?"

Nighttime:
 * "Be careful, youkai are most dangerous during the night."

During rain:
 * "It's raining again. I wonder what obscure youkai is attempting world domination this time?"

During a Blood Moon:
 * "This reminds me of the Scarlet Mist incident."

During a Solar Eclipse:
 * "This is definitely some sort of incident."

During Martian Madness:
 * "Hey, an alien!"

While on the Surface:
 * "There was a girl back home who came from the heavens... I think I could recall what her clothes looked like if I could get on top of one of those clouds..."
 * "A fairy from hell moved into my homeland recently. Her clothes were very strange, maybe seeing what hell looks like could help me remember them?"

While in a Glowing Mushroom biome:
 * "Marisa would love it here."

No boss has been defeated yet:
 * "I wonder if anyone else from my home ended up here."
 * "I don't think I was supposed to end up here, but maybe some familiar faces will show up as well. Though I think you'll need something to lure them in..."

After any Tier 1 boss is defeated:
 * "It seems like you can handle your own out there. I have more items in stock - maybe they'll help you out."
 * "The people I know are very hardy - they won't die after getting beat down. Chances are, they'll want a rematch too."

If Lily White is defeated:
 * "Does this place even have seasons?"

If Rumia is defeated:
 * "You met Rumia and didn't get eaten - good for you!"

If Eternity Larva is defeated:
 * "Fairies love getting into fights, as I'm sure you've noticed."

After any Tier 2 boss is defeated:
 * "Most humans I know can't handle the weakest of youkai... I wonder what makes you special."
 * "You've proven yourself again. With any luck, you might just get rid of that [red / purple] mess outside." (depending on whether the world was generated with Crimson or Corruption).

If Hina Kagiyama is defeated:
 * "Fighting a misfortune god can't be a good omen..."

If Sekibanki is defeated:
 * "I think I might've seen that girl with the detachable head in the Human Village once... nah, can't be."

After any Tier 3 boss is defeated:
 * "Things are changing, alright. This world gets more bizarre the longer I'm in it."
 * "Luckily, with all these new materials, I can gather more things to tinker with. You'll need better gear for whatever's out there."
 * "Normally, danmaku is about 'who can make the prettiest', but it seems like nobody wants to follow the rules here... Now it's 'who can kill the other more quickly'."

If Nitori Kawashiro is defeated:
 * "Kappa technology sure is advanced, isn't it?"

If Medicine Melancholy is defeated:
 * "I once read about 'chemical weapons' in an Outside World book. Do you think that doll would qualify?"

After any Tier 4 boss is defeated:
 * "You're beginning to rival some pretty powerful beings from my land. However, you still have a ways to go, so... Don't let it go to your head."
 * "I'm enjoying the scenery, but... With all the evil lurking out there, I feel like I'm under house arrest."

If Minamitsu Murasa is defeated:
 * "That Ship Phantom must have been really happy to see the ocean again after so long."

If Alice Margatroid is defeated:
 * "You met the puppeteer? She's usually even more of a recluse than I am."

After any Tier 5 boss is defeated:
 * "Back home must be going through a pretty boring time if the likes of these girls are showing up."
 * "The more I look around, the more I find random magical items lying around... Is this that gap youkai's doing?"

If Sakuya Izayoi is defeated:
 * "The mansion's maid is one of my best customers, you know. She actually pays for the things she takes."

If Seija Kijin is defeated:
 * "I still feel dizzy..."

After any Tier 6 boss is defeated:
 * "Congratulations, you're an honorary incident solver."
 * "These battles are getting pretty intense. I like to stay out of it, but I can't help but watch you fight."

If Toyosatomimi no Miko is defeated:
 * "That Taoist is very flashy, isn't she? She even won a fireworks contest back home recently."

If Kaguya Houraisan is defeated:
 * "It's pretty rare to see the Lunarian exiles outside of the bamboo forest. You should count yourself lucky, I guess."

After any Tier 7 boss is defeated:
 * "Are you a hidden god?"
 * "Where's the sake? I feel like this calls for a celebration."
 * "You've grown more powerful than even some of the strongest from home. Don't get arrogant, though. There's always gonna be someone stronger than you."

Trivia

 * The Curio Trader is based on Rinnosuke Morichika (to the point where his only name is Rinnosuke). Him using the Kusanagi to defend himself and it being the only item he initially has in stock is a reference to him being the canonical owner of the sword after finding it in a pile of trash from Marisa's house.
 * Rinnosuke's quote "Sometimes it feels weird not being the only male around" is a reference to the fact that Touhou's cast is almost completely female, and he is the only named humanoid character to be male.