Phoenix Wright, Apollo Justice, and Athena Cykes, Ace Attorneys, are as close as you're ever going to see to hot-blooded lawyers, though they tend to be a bit calmer and quieter outside of the courtroom.
Apollo Justice takes VOICE TRAINING so he can be this hot-blooded.
The dumb variant of this trope - Detective Dick Gumshoe~!
Dick Gumshoe is so hot-blooded that every other line of his tends to come with plenty of screen-shaking and violent sound effects.
Akio Furukawa of CLANNAD, beyond a doubt. All he needs is a mecha.
The heroine (default name Hiyoko Tousaka) from Hatoful Boyfriend screams, "MY HUNTER-GATHERER BLOOD BOILS! AAAAAAAAAAAAARGH!"
Oko San. His route is him and Hiyoko trying to out-ham each other in the name of love (and pudding).
If you listen to Satoshi's image song, you notice how surprisingly hot blooded he is. Satoshi acted similar to Keiichi in Onikakushi-hen, according to Rena, meaning they can't be too different.
Speaking of Rena, when she isn't really sweet/calm or under the Hate Plague, or someone is hallucinating her being maniacal. She is just as Hot-Blooded as Keiichi. It really shows in the Minagoroshi manga and sound novels.
In Umineko: When They Cry, Battler is Hot-Blooded in a similar way to Keiichi. However, in this story it's deconstructed; his Hot-Blooded tendencies actually keep him from figuring out Beatrice's game, since he never stops to consider why she's challenging him in the first place and remains too focused on defeating her out of a vague sense of justice. He constantly misses the point of the clues she leaves for him in the form of "magic", and he can be very Innocently Insensitive at times. Once he finally realizes the truth in EP5, his Hot-Blooded-ness is toned down.
Koujaku from the BL VN DRAM Atical Murder, whose specialty is riling up all the seemingly stoic people he meets as soon as he meets them because he thinks they're up to no good (he's, perhaps unsurprisingly, right about this). Which is basically every seemingly stoic character in the game (there are a number of them).
Ishimaru from Dangan Ronpa is an interesting case of a Hot-BloodedClass Representative who's VERY SERIOUS about order and discipline and following the rules. He gets even more Hot-Blooded (and foul-mouthed) when he's possessed by Oowada's spirit (or just goes crazy.)