難問: difficult problem / 南門: south gate

これは何ですか: what is this?

(slang) adult fans of an anime, a manga aimed at children

(slang) Alternative form of 大きいお友達

龍野: / Tatsuno (a city in Hyōgo Prefecture, Japan)

成り立つ: to consist of, to be composed of; to reach, to be concluded; to be buildable, to be constructible.

fighting with tachi (swords) / (figuratively, often used with negation) competition

shooting while standing

to shoot while standing

to fight with tachi (swords) / (figuratively) to compete