Midori Komaki from Devil Survivor.
Devil Survivor is a very grounded, very dark game about what happens when you put a section of Tokyo on lockdown while demons invade and give regular, very fallibly humans control of those demons.
Midori above is a cosplayer caught inside the lockdown and thinks she's a magical girl who can save people with the power of love.
She's annoying, completely oblivious to the shit happening around her and all the problems her "power of love" mindset causes, but it just works
so. damn. well. Given SMT's recent games, you'd be forgiven for thinking she's in the game to pander to the anime waifu crown. She's actually quite the opposite: a deliberate deconstruction of the magical girl archetype, much like the game in general is a deconstruction of games like Pokémon. She's even better in the remake, Overclocked, courtesy of Erin Fitzgerald, who gave her the most obnoxious voice. Think of Persona 4 Golden Chie but on crack.
Best of all, if she survives until the end of the story, she receives some solid character development and the game actually partially reconstructs her idealism... by causing a Jack Frost to evolve into Black Frost out of idealism alone and letting him join your party as a full fledged party leader.