Prologue
Late summer in Gensokyo. The spring our heroes, Marisa and Reimu, have spent in several places like Hakugyokurou, Scarlet Devil Mansion (or its library, in Marisa's case) and Youkai Mountain with some of their friends has come to an end long ago, and the fantastic adventures they spent this summer as well. The temperatures should have gone down by now, but it was still hot. Really hot.
"Say, can we turn off the sun?", Marisa muttered. She was lying inside the Hakurei shrine, with Reimu sitting not far from her.
"I don't think we're qualified.", Reimu replied with a yawn.
"Is this heat wave really making sense?", Marisa asked again.
"Nope. But not many things here do anyway.", said Alice, who just entered the room.
"People usually knock when they enter someone else's house.", Yukari laughed, who just appeared floating from her boundary above them, nearby the ceiling.
"You're the last person to tell that to anyone.", Reimu said angrily.
"Except her.", Alice added, gesturing towards Marisa, who seemed to be looking for something inside one of the boxes.
"No food there.", Reimu quickly said, and Marisa shrugged and lay back down.
"Anyway, this heat wave has been going on for a week. I can't stand it! I think Hell was colder than how it is now.", Marisa complained.
"That might be the least of our problems.", a voice said. Everyone looked at the door now, to find a Youkai with purple hair and clothes, known as Patchouli Knowledge.
"Rare to see you out here, Patchy.", Marisa said happily.
"It's serious business this time. Can't afford to send someone in place.", she said quickly. "Not that they didn't come.", Patchouli added and pointed behind her to show Meiling, Sakuya and Remilia.
"What is this, a meeting place?", Reimu asked angrily.
"We all just came to visit." everyone said in unison.
"Anyway, the heat issue here is serious.", Patchy continued.
"I don't see the problem. More sunlight will only keep you Youkai at bay.", Reimu argued.
"Did you really not notice that I didn't bring my parasol this time?", Remilia asked with a smile.
"In this heat? And I was hoping to have some fried Vampire.", Marisa sighed.
"Don't mess up the food chain please.", Remilia sweat-dropped.
"Anyway, we've come because our job is in stake.", Sakuya spoke up.
"We'll never find another job here!", Meiling called sadly.
"Don't forget my library...", Patchouli added.
"And the whole mansion.", Remilia reminded them.
"So what are you coming here for? If it's your problem go fix it yourself.", Alice yawned.
"It's not just our problem.", Remilia said angrily.
"So what is the problem?", Reimu demanded.
"This.", Patchouli said and opened a door facing the Misty Lake. Only it wasn't misty. At all.
"I could see your place from here if it wasn't for the giant pillar of light above the lake!", Marisa called in surprise.
"This is the reason I don't need my parasol.", Remilia said.
"I'm not following you.", Reimu sweat-dropped.
"Most of the light in Gensokyo is focused towards the Misty Lake. Which is why there isn't a lot of light there. But all that focused light creates heat, which can't be focused. That's why it's been so hot the last week. It's just that the light became so strong today it was able to vaporize all the mist and let us see it.", Patchy explained.
"Oh, now I see the problem.", Yukari suddenly said. "If that glacier in the bottom of the lake melts, most of Gensokyo will be flooded.".
"Sucks to be you!", she added with a chuckle.
"You know about the glacier too?", Patchouli asked in surprise.
"I know what's in it as well, but that's a secret.", the Youkai giggled.
Patchouli frowned, but turned towards Reimu, Marisa and Alice. "We need your help finding out the cause of this problem.".
"And why should we help you?", Marisa teased.
"Because the Forest of Magic, along with your houses will be caught in the flood as well.", Remilia said with a smile.
"Well that's good and all, but the cause of this is probably inside the lake. We can't breathe there.", Reimu said angrily.
"There's an algae that's usually floating on the lake.", Patchouli started and opened the book she was carrying. "It will let you breathe underwater for 24 hours if you eat it.", she said and showed them the picture of a deep green algae with the shape of a star.
"It's pointless for all of us to go. We need to decide who will do it.", Reimu said.
"I say the strongest should go!", Meiling called and punched the air.
"That leaves you out then.", Sakuya laughed. Meiling rolled her eyes.
"I say the fastest should go!", Marisa called and flew outside on her broom and was back 2 seconds later.
"I think the one to get there first will do it.", Yukari suggested.
"Right now?", Alice asked in surprise.
"Nope. We need to follow the light to find the criminal. We won't find him like this.", she answered and pointed towards the lake, where the light was already disappearing, as was the sun from the sky.
"Fine. We'll go tomorrow.", Reimu sighed.
"But for tonight... Let's feast!", Yukari called and tossed everyone a bottle of Sake from her boundary.