Looking for a Well-Written, Completed Mystery with a Great Ensemble Cast, No Clichés, and Brain-Teasing Plot Twists

Looking for stories like Domain River, The Weird House, and The Ten Days of the End. Romance or no romance is fine, as long as there isn't a harem. I want a smart protagonist who isn't absurdly overpowered, and who's kind without being a pushover. The ensemble cast should be well written, and the supporting characters should get their own stories too.