Manga that the MC is not a simp or clumsy(serious type)

[Shiny]

The first manga which comes to mind is Death Note.

[custodes]

Hmm, those requirements definitely inform me that you must be informed not to read Rental Girlfriend...the most frustrating series so far, with the ML being a super "simp".

[Lily Garden]

Are you looking for only Male MCs or would you be also interested in a series with a Female MC?

[Raitoiro]

You could try The Faraway Paladin, the manga is available on JNC but unless you only want manga you should rather go with the LN (which are also on JNC).
Either way it's a great story and the MC doesn't simp, after all you can't simp if you don't have any girl around you

[Paul Nebeling]

@Raitoiro I'm not so sure I would say the MC of Faraway Paladin doesn't have any girls around him. (Spoiler for obvious reason)

spoiler

I also recall there was a "regular" girl that the future seemed to indicate he would cross paths with. Don't quote me on that though. It's been a long time since I read that story.

[Raitoiro]

@Paul-Nebeling True it's not like there's no women, at all

spoiler

[Folker46]

The Apothecary Diaries. The MC is female and has little to no interest in having a romantic relationship with anyone, she just wants to work of her herbs and poisons and not be bothered. That she keeps getting pulled into other people's problems just annoys her. The manga is better than the LN I feel.

[poisonedbite]

The most unsimp I can think of is probably parallel paradise lmfao. it's extremely nsfw.

[paulnamida]

And now I'm again reminded of New Life+ and am sad. God, I loved that series.

Let's see, manga with male MC being indifferent towards girls...

Faraway Paladin comes to mind as some others pointed out.

There's that one about the mage that goes back in time to being a child in order to learn magic that suits him better, since he's an old man at heart, despite him meeting a bunch of girls and all of them falling for him, he sees them as grand daughters. The title started with "Kouritsuchuu madoushi" or something like that. It's not licensed as far as I know, though.

Death March to the Parallel World Rhapsody also kind of checks, MC gets surrounded by little girls but he's not into them, he does find some love interests along the series but he's neither a simp nor clumsy when it comes to relationships, he's actually quite a Chad. This one is licensed. The manga is waaaaay behind when compared to the LN though.

Arifureta also has a serious MC, although he's a simp for Yue, he's pretty much ruthless to everyone else, and it's not like the romantic scenes are that long or take away too much from the story in the first place, it's an action series in nature.

None of these are kuudere type MCs though.

[Korppi]

Hazure Skill: The Guild Member with a Worthless Skill Is Actually a Legendary Assassin (both novel and manga licensed in English)
-mc seeks a normal life, with various results

The World's Finest Assassin Gets Reincarnated in Another World as an Aristocrat (both manga and novel licensed in English)
-goddess asks mc to kill the hero

The Magic in this Other World is Too Far Behind! (both manga and light novel are licensed by j-novel, novel stalled by author)
-hidden magician gets whisked into a world with primitive magic

All three have mcs who are pretty indifferent to any distractions of the opposite sex
...though I wonder if the OP will read these posts, it's been over a year? (noticed while writing this)

[pcj]

JK Haru is a Sex Worker in Another World - MC is female, and her job is sex, but she's all business about it and it's very late in the story before she even starts thinking about romance. And there are guys who are into her, including one who got summoned with her from Japan, who she pretty much ignores. She's also extremely competent, solving mysteries and engineering ways to rescue people from various situations along the way.

[Kilocron]

@pcj I wouldn't call her a simp or anything, but she mentions several times that she really enjoys all the sex, at least with decent partners.

As for my answers hmmm....

Well on JNC what immediately comes to mind is

Born to Remaster the Blade : Inglis could give a crap less about male or females. She only wants battle!
Hell Mode - Allen, while he has females in his part, only looks at the utility of them and if they can help him grind more XP lol.

There are more I'm sure but... lazy....

[pcj]

@kilocron said in Manga that the MC is not a simp or clumsy(serious type):

@pcj I wouldn't call her a simp or anything, but she mentions several times that she really enjoys all the sex, at least with decent partners.

Yeah, enjoying sex is different from pursuing romance though, especially in the industry she's working in.