From Art of Fighting 3: The Path of the Warrior and based on her appearance in The King of Fighters '99: Millennium Battle, it's Kasumi Todoh! She's a favourite of mine from the AoF series, but it's surprising to see her AoF3 / KOF96 design is a bit different from later ones- her hair is in a more obvious ponytail in later games, for one thing. If you're wondering about the book and the caption here, one of her win poses in a few games has her whip out an English phrase book and say "Come back when you grow up!" to her opponent in English. That's dedication to trash talk, doing so in a different language!
#MS Paint World
From the Mega Man 6 sprite hack Roll-chan 6, it's Roll with the Tango Power Adaptor! I've decided that I'm gonna draw Roll using my favourite weapon from each of the six NES Mega Man games now I've beaten them. I've done HARD KNUCKLE from Mega Man 3 already so here's my favourite weapon from 6, the Power Adaptor. She doesn't fuse with Rush, she fuses with Tango instead, and it looks like she gets cat ears, so I decided to run with that. I guess I'm a fan of punching robots in these games, huh~
From Arknights, it's Muelsyse of Rhine Labs! She debuted in the game as really fun NPC but eventually got upgraded to a recruitable Operator. She's a water elf who can make water-clones of herself which she often uses to flummox her enemies or just tease the Doctor a little. Her English VA is especially great with her voice lines, which have a slight playfulness to them, she clearly has a bit of fun while she's out there making water clones and posing with her umbrella. She's a favourite of mine, can you tell?
From DoDonPachi SaiDaiOuJou, it's the Operator! Voiced by Asami Shimoda (voice of the Futami twins from THE iDOLM@STER and the Vocaloid Kagamine twins), she appears from time to time to encourage you in your difficult fight. Sure, I'm not very good at this kind of game, but you know what I do like? Drawing cute operators. I like to think she hangs out with Nancy from Chase H.Q. and that lady ffrom Armored Warriors in her time off. Probably.