Counterattack System appeared when I'm already At The Mahayana Realm - Chapter 756 - 755: Both of you can go on together.

「Shimizu-san, you dyed your hair black.」「Ah, yes.」「Why did you dye it all of a sudden?」「Because…yesterday…」Shimizu-san, who sat next to me and had dyed her hair from blonde to black gradually lowered her voice, slightly blushed, and laid her face down on the desk.

Ayaan is a young resident aspiring to be a surgeon, the final stage of a full on graduated plague doctor. However, in her attempt to redeem herself after a sudden discontinuation, she finds herself unravelling mysteries about her institution that are rather gut wrenching. Stick around and watch her persevere in a world full of monsters; creatures and humans alike.

He Lang died by his own hands for the sake of his imperial younger brother’s ambition, whom he loved. He was offered to be reborn in exchange for giving up his past romantic feelings. Reborn without the burden of his romantic feelings, he brings with him a manual to new worlds. He wholeheartedly followed the instructions of the manual to complete the tasks, not knowing that the originally slag gong was blackening…
He pleaded to his affectionate Emperor brother to release him, he pleaded to the paranoid prisoner next door, but until the end he remained baffled.
In the end, he discovered that the full name of the manual was – “Slag Shou Cultivating Manual”
Σ (っ ° ° °;) っ!

- Description from Novelupdates

“What’s my class?”[Beast Tamer – Class E]“..Seriously?”Lee Min-Jae was a workaholic with no social life who died slumped over his keyboard. When he opened his eyes, he was in an RPG-like world — but with the worst class imaginable: Tamer.Tamers were seen as useless. Weak. Limited to disloyal, expensive-to-keep wild monsters.But he wasn’t just any fool. He was a systems-obsessed gamer, an expert at finding exploits and shortcuts.With his cold, analytical mind, he chose to break the game’s rules — by leveraging the most reviled mechanic of all: contracts.Where others saw abomination, he saw an exploit. And he was ready to turn the worst class into something unbeatable.---------------This story have:[Adventure][Smut][MSmut] (no NTR).[Harem][System / LitRPG][Strategy] - cold planning, exploiting mechanics, creative use of abilities.[Cold and Calculating Protagonist] – no naive romance.[Worldbuildin] – rules, politics, economy.[No NTR] – the protagonist is not betrayed, no passive humiliation content.