Who killed the clown?

Well I may not know who killed Bain, However I do Know Team Gurren is openly recruiting to try to make sure we all escape here!

Do childrens these daisys always weared such pointy grasses?

I take Senor Cardgage as the main suspect of the kill.

By the time the kill happened, everyone was in the following locations:
- Kamina: In the gym, along with Travis Touchdown.
- Travis: In the gym, with Kamina. Kira's a witness of both.
- Kira: Playing with Shear Heart Attack. Not near the Rec Room.
- Harold: Playing music, on the first floor. Not near the Rec Room.
- Sans: In his room, presumably sleeping.
- Bowlywood: Lying down in the walkway.

This leaves for only one suspect, and that's Cardgage. Since he's not posting an actual account and joking around with silly stupid games instead of being helpful, I'm afraid it's the most likely candidate to be Jason Voorhees, disguise used to kill Bain in the Rec Room. He waited for Bain to get in, knocked him out and made a small circle of fire to get him slightly burnt, using what's presumed to be a pointy weapon to make the bruise on his head, thus killing him at the spot.

That's all I have to say.

Aaaaaand you voted for @Senor Cardgage

And guess what, you're CORRECT! Cardgage walked by Bain by complete coincidence, in which he decided to knock the hacker out with a tree branch. That didn't work, so he went for a huge punch instead. The masked man dragged the body to the REC ROOM, set it on fire with all of his tree branches (there were a lot, trust me) and a firestarter kit and left the scene.

Sucks that HOLLYWOOD BOWL planned his suicide so meticulously, only to have his plan thwarted by his own god! Religion can be a bitch, sometimes.

And so, let's start PUNISHMENT TIME!

SENOR CARDGAGE is sent to an undisclosed location, far away from civilization. In front of him is a campfire and a tent. A whole bunch of BEAR TRAPS fall down from the sky, landing in front of him, with a message written on one of them: "They're coming".

CARDGAGE quickly sets up a whole bunch of traps around the campfire, having a KNIFE ready next to him. He hears steps coming towards him: bears of black and white varieties. They all come charging towards him with intense speed! One of the bears sets off one of the traps, but no matter, they're too furious to care. CARDGAGE can do nothing but point the knife at the animals as they pounce at him, shredding his clothes apart and, very shortly, his skin and flesh.

Afterwards, the bears cook his body parts up by the campfire, having a delicious dinner.

Yummy!

You definitely guessed it, SENOR CARDGAGE was the owner of the CAMPER'S SHOP!

Spoiler: Show

+ Your shop is mobile: At the beginning of the game or at the beginning of every investigation phase, you decide where you set shop in the map. There are no limitations!
+ You can end your day and sleep in the camper's shop.
+ You have a 25% price reduction to all items you buy from your own store.
- You're not good with technology: You cannot use electrical items to enhance your shop (Cameras, Turrets, Alarms, etc.)

With that, he was also the temporary owner of BAIN's VAPE SHOP!

Spoiler: Show

+ You start with a vape.
+ You're so good at vaping, the effects from the vapes you use are more potent.
+ You get a 50% price reduction to all items you buy from your own store.
- You're too sensitive to cigarettes and weed. You start choking a lot if you inhale non-vaping fumes.

...Wait, what's that? I hear something coming from MONOKUMA'S SHOP...

My coma's toast.