"So basically, I threw in everything I like and somehow a comic came out"
This is a self indulgent manga from Chrono Nanae who is popular for their shounen manga, "Peacemaker Kurogane".
It's about a hedonistic master vampire and the devout Catholic half cyborg vampire who hunts other vampires(a mash up of tropes lol) who feeds on him and their relationship while they try to solve cases about a mysterious drug that has been turning humans into vampires.
A slow developing romance between Sugiki, a standard ballroom dancer, and Suzuki, a latin american dancer, and their passion for ballroom dancing.
This is not a slow developing romance since they did start dating early on but the charm of this series is the romcom story telling about a couple with different lifestyles, one is a cop and another is a yakuza.
A manga about a boy accidentally time travelling to the past and meets another boy who was in love with his grandfather and mistook him for the young version of his grandpa who ran away from home at that time.
Koimonogatari