Hello,

I'm looking for silent protagonists, but outside of the category of romance and preferably something that's not a slice of life either. They don't have to be mute but something like the main character in Kokou no Hito, Noblesse or even Freesia is what I'm looking for.

Thanks for the help!

Maybe Blame!? I've never read it though.

I think Blame! fits pretty nicely.

The protagonist in Mahou Gyoushounin Roma doesn't talk about anything outside of work for the most part, but she becomes more talkative in the backstory/flashback chapters.

Sakai no Musume - Cat in the Car is a bit quirky premise-wise, but should fit.

The protagonist in Shion no Ou, though if memory serves she starts to talk later on.

Kimi ni Shika Kikoenai
Alyosha!
Hotel Tantei Doll
Usemono Yado
Jiraishin -- Somewhat similar to Freesia, though the protagonist is firmly on the side of justice.

Slice-of-life titles which I figured I'd mention just in case:
Helen ESP
Tonari no Seki-kun
Flat (AOGIRI Natsu)

Sket Dance - I guess this depends on how rigid your definition of silent is. Switch doesn't speak throughout almost the entire series but does use a computer to do his speaking for him. This does have a few chapters though where he's without his laptop for one reason or another and must try to communicate in writing or hand signals. Only series off the top of my head I could think of for this.

Golgo 13: Old manga about a killer for hire. Strong, silent type. He does talk but very rarely.

Dogs - Bullets & Carnage: Heine, one of the 2 MCs is like that.

Err... It's a shoujo but, Suijin no Hanayome. Her voice gets taken/locked away. Haha