Fantasy

A fantasy otherworld where diverse monsters and races exist.
Most people can use magic if they undergo proper training, but some cannot due to their magical capacity.

Dungeon: Mysterious structures naturally generated by powerful magic. Space is distorted, and they are almost always larger than they appear.
Many monsters inhabit them, but powerful magical tools are often found inside.
Adventurers often frequent them to sell monster materials, as monsters are easy to find there.

Monsters, adventurers, and some magical tools are assigned the following ranks based on their strength.
D rank: Equivalent to an ordinary person.
C rank: Equivalent to an adventurer who has undergone some training.
B rank: Equivalent to an intermediate adventurer. This is considered the limit achievable through effort alone.
A rank: Equivalent to a seasoned adventurer with talent.
S rank: Overwhelming talent is essential. Off the charts. Capable of easily destroying a nation. Only a few monsters, adventurers, and magical tools exist at this rank.