The System Mistook Me for a Cat - Chapter 215

There exists eight hardships of human life- living, aging, being sick, dying, resenting, parting with loved ones, being unable to let go, and being unable obtain something.

In each life, each person will experience their own hardship. Once they obtain happiness, they are furthermore unable to let go. Whether it would be heartfelt love or resenting someone down to the bone, would it matter? As long as that person’s bone has my name, it would be good.

- Description from Novelupdates

Eren Idril died as an old, decrepit, and piss-poor adventurer by the maws of a D-Rank monster. He had a lot of unfulfilled dreams and desires that couldn't see the light of the day after the light in his own eyes died down.

But fortunately for him and unfortunately for the world, that wasn't his end. Eren was somehow dived back in time when he was a mere teen, attending Lionheart Academy for adventurers.

When life gives him a second chance, Eren decides to exploit it to its fullest. Experience his vile deeds as he partakes in them without feeling the slightest bit of hesitation.

The great journey of an ordinary martial artist.“Once your habit is tainted, you have no choice but to live as a dog forever. Do not turn the wolf inside you into a dog.”