Shameless self-promoting time!
Pretty much most of my stories feature crazy and powerful MCs, but I shall name a few that are very powerful.
Zenar 24: Ava Kalesidia is a Zenar, and a powerful one at that, and a normal Zenar can destroy armies by themselves.
The Wandering Last Boss: Elsaline is the world's hardest raid boss that has only been beaten twice in a game almost the entire world plays.
The Apostle Of War: Ai is, without a doubt, incredible strong. Though, compared to the others, she still struggles with enemies sometimes. It'll make sense why if ya read it.
Pissed Off Loli: The MC is most definitely overpowered but, like Ai, they still struggle with certain things.
The Clown And The Pink-Haired Delinquent: Said Clown is a highly skilled mercenary with a violence problem, and is most definitely Crazy.
Her Traitor: The cute story about one hardened badass and her former partner, now turned into a insane monster, and their journey together trying to survive the end of the world.
Magical Girl Grape: Also known as the Magical Girl Of Suffering, the MC is very strong and has almost no problems defeating the monsters out to harm others. However, that story is heavily psychological and the MC's biggest problem is in her own mind. Read it if ya want to understand.
The rest are less into the overpowered spectrum in the sense of the story.
The Princess And Her Warmonger: Sharia Airella, the secondary main protagonist, is definitely overpowered and, since she is a Warmonger, crazy, and she cannot be manipulated since she has too much experience. However, that story isn't as focused on action as the others and, the primary MC, Isalene, is weak in terms of power.
Sardinia! What Is Innocence?: A psychological story with many MCs, and all but a few of them are powerful. However, the entire story is dark and not focused on fighting.
Trying To Raise The Tyrant Villain: Both Sella and Cherry are powerful, especially Sella in the beginning, yet, the story is more psychological.
The Noble And The Outcast: The secondary main character, Sovanna, is both a psychopath as well as a highly skilled warrior who does the manipulating instead of being manipulated.
Candy Pop!: This is a story with episodes, or smaller stories centering around a small cast and one highly skilled, sadistic and crazy hitman named Candy Pop.
Poor Little Kallie: A horror story set in an orphanage, Kallie, one of the main protagonist, is a very smart and ruthless girl who is willing to do anything to get her revenge on the head of the orphanage. She has the uncanny ability to make anything a weapon, and is more weapon than kid.
Rashie And Her Killer Robot: An insane loli idol suddenly finds herself the host of a unknown man-killing robot trying to restore their memories. Needless to say, chaos ensues. The reason why this is here is because the duo are not that overpowered.
Sugar And Meat: Sweets And Flesh!: A story about a high school being infected with a strange virus known as 'Magic'. This story follows Yuu, someone who is not only immune to the infection, but can cure it, and Julia, the most feared student in the school who loves to make pastries and sweets out of her victims, and the unlikely alliance between the two.
And that's all for now. Hope ya enjoy this!