The plot involves Rimuru's journey from being a rather weak (initially) slime to becoming a very powerful being. He meets many interesting characters. For example, there are the goblins he befriends early on. Rimuru helps them improve their living conditions. As the story progresses, he also has to deal with the threat of other more powerful monsters and even some human kingdoms that view his growing power with suspicion. In general, it's a story full of adventure, growth, and the forging of relationships in a magical and dangerous world.
The light novel 'Akame ga Kill!' also has an OP female MC in Akame. She is a highly trained assassin with a powerful teigu (a special weapon). Her skills in combat and stealth are top - notch, allowing her to take on much stronger opponents.
One of the best female mc novels is 'Pride and Prejudice'. Elizabeth Bennet is a remarkable female protagonist. Her strong will, intelligence, and independent thinking make her stand out. Another is 'Jane Eyre'. Jane is a complex and inspiring character who endures hardships and remains true to herself. Also, 'The Hunger Games' with Katniss Everdeen as the female mc. She is brave and resourceful, fighting for survival and justice in a cruel world.
The main character is Rimuru Tempest. He is a slime who has unique powers and a great deal of charisma. Another important character is Veldora, the storm dragon who befriends Rimuru. There is also Shizu, a human who has an impact on Rimuru's early development. And then there are characters like Benimaru, a powerful ogre who becomes one of Rimuru's loyal followers.