What kind of manga is this? its just a bunch of click bait in every first panel/page of chapter.
if you want to train your D like the way you inhale and exhale this is a good manga for you.
Solo again? where is the duo the threesome foursome maybe?
come'on anything that is not the same name of what popular these days. this is just authors trying to be something like those popular manga manwha whatever, instead of trying to be a bit more unique or to be a start of a popular theme or...