A Hentai System in the World of Danmachi - Chapter 196 - 195 - Ishtar is annoying.

have you heard of it?

If you turn on the music player in the dead of night, put on headphones, hide your head in the quilt, and listen to the looped single repeatedly.

Fall asleep after looping forty-four times. If you are unlucky and open your eyes again, you will no longer be lying on your own bed, but will enter a strange space that is completely isolated from reality.

That space… On the surface, it looks like the places we usually see, such as our bedroom, living room at home, underground garage, bathroom, basketball court, construction site, etc. But if you look closely, you will find that it is different. …Everything is different.

====

This is the experience of an ordinary person who, after acquiring superpowers, transforms and grows step by step in a blind corner, reaching the ultimate level.

- Description from novelbuddy

Matthew grew up in a decent family filled up with hopes, dreams and big heart, but living a shitty life which were suddenly demised with the unexpected turn with a mishap. With the new changes of his body, he finds new powers and wondering into new dimensions. This new enigmatic power is suddenly taking soul form his body and making him something beyond of his imaginations.... His tasks are unclear but he has to take soul of each demon he meets in his path... With his powers he has bigger responsibilities in each of the dimension which is beyond explanation…

An unnamed 34-year-old Japanese NEET is evicted from his home following his parents' death.

Upon some self-introspection, he concludes that his life was ultimately pointless.

Walking down a street he intercepts a speeding truck heading towards a group of teenagers, in an attempt to do something meaningful for once in his life he manages to pull one of them out of harm's way before getting himself in the way of the truck and dying.

Awakening in a baby's body, he realizes he has been reincarnated in a world of sword and sorcery.

He resolves to become successful in his new life, discarding his past identity for his new life as Rudeus Greyrat.

Kōdo Ikusei Senior High School, a leading prestigious school with state-of-the-art facilities where nearly 100% of students go on to university or find employment. The students there have the freedom to wear any hairstyle and bring any personal effects they desire. Kōdo Ikusei is a paradise-like school, but the truth is that only the most superior of students receive favorable treatment.

The protagonist Kiyotaka Ayanokōji is a student of D-class, which is where the school dumps its “inferior” students in order to ridicule them. For a certain reason, Kiyotaka was careless on his entrance examination, and was put in D-class. After meeting Suzune Horikita and Kikyō Kushida, two other students in his class, Kiyotaka’s situation begins to change.