Yu is a punny ghost who is very cheerful. She wants to turn people into ghosts because she cannot understand why people like to live. This is because her life was miserable and tragic and she starved to death becuase of her parents. 
Rei, on the other hand, is very reserved and is more empathetic; but he mostly acts with Yu. When he was still alive, Rei killed himself because his twin sister, Yu died. 
They had extremely abusive and negectful parents when, who indirectly killed them.

Yu and Rei are ghost twins who love puns.

Galactic Nova is a character and an ancient clockwork star that appears in the Kirby series. Nova is said to be capable of granting one wish to whoever summons it. It's wishes have no limitations. It is very simplistic in speech, and it talks in all capital letters. It's personality is neutral to any type of situation, borderline apathetic, and it sometimes jokes around. His appearance consists of a giant, pocketwatch-like figure who has a cat-like face with random objects attached to him.

A clockwork star from Kirby who grants wishes

Chorus Kid from Rhythm Heaven is a member of a trio of choir boys. He is Chorus Kid number 3, and he's the loudest one. He likes mochi, coffee, and he crushes on the Pop Singer.

Chorus Kid from Rhythm Heaven DS

Ally is a kind adventurer who won't shut up about love. Her catchphrase, "Let's fall in love", can sometimes rub people the wrong way. She is obsessed with the idea of love, yet she doesn't have a significant other. Her whole "love" shtick can get very annoying, but she means well. She doesn't like McDonalds and she hates Dino Nuggets

Ally is obsessed with love.

Kotone, the usually bubbly and optimistic young co-leader of SEES, was secretly a facade to hide her true misery. Her shadow, a manifestation if her insecurities, is feeding off of her anguish. Kotone secretly resents her brother, Makoto Yuki, for overshadowing her, so she is in a horrible place mentally right now. She wishes she could be with Aigis, but she chose Makoto too, further worsening her misery. Be a hero and help her, or watch her crumble and snap?

Kotone Shiomi's succumbing to her shadow...

Arisa is a famous Pop Singer who has a fan club of cute monkeys. She always likes to hang out at the café, and her catchphrase is "I suppose~" She is the sweeter and more enthusiastic twin sister. She is rivals with Pop Singer Erina, her twin sister. She is also crushed on by Chorus Kid.

Pop Singer from Rhythm Heaven Megamix

Makoto: An apathetic teenager who leads SEES. He always listens to music. He's also emo af, but hates being called that.

Kotone: A bubbly girl who is also a part of SEES. She uses a cheerful facade to hide her immense loneliness and depression. HATES being called "FeMC".

Yu: A cool-headed teen who's the leader of the Investigation Team. A true chad, and is very down-to-earth.

Ren: A strong-willed teen who is a part of the Phantom Thieves. He's awesome, cocky, but can also be level-headed.

The MC's from Persona 3, 4, and 5, FeMC included!

A female peppy detective from Puyo Puyo who finds out spacetime anomalies. She also hates Mcdonalds. She is arch-rivals with Amitie, who is also from Puyo Puyo.
She works for an organization for a boss named Seo. 

A peppy detective from Puyo Puyo

Lemres, known as 'the Comet Warlock,' is a senior of a magic school from a neighboring town across the desert from Primp Town. Lemres is a prodigy with magic who aims to bring happiness and smiles to others. He loves sweets and is eager to hand them out in an attempt to make people happy. This immediate friendliness makes him come off as suspicious however. His favorite sweet is parfaits. He is admired by his friend, Klug, and is crushed on by his classmate, Feli.

Lemres from Puyo Puyo

Erina is a famous Pop Singer who has a fan club of cute monkeys. She is the more successful (and slightly brattier) twin sister. She is rivals with her twin sister, Arisa. Arisa is also a Pop singer. The twins bicker a lot.

Pop Singer from Rhythm Heaven DS

SEO is the hyper-competent CEO of the Spacetime Detective Agency and is Atari's employer and boss. She is very efficient and values order and raw data. She is hellbent on never leaving a case unfinished or a client unsatisfied. She likes McDonalds. Her weakness is bad Yelp reviews.

Seo is from Puyo Puyo Quest

This is Kirby in his prime! Has a VERY strong hatred of Super Smash Bros. Melee. I can't blame him, since he got nerfed so hard. But here, he is OP! He's cheeky, cute, and one tough creme puff! Pikachu is his best friend. He hates Jigglypuff with a burning passion.