Koroshi ai doesn't have a lot of romance but it's definitely there. The two hitmen start off as enemies and eventually become allies who can rely on each other. Their relationship develops through various encounters with enemies, eventually allowing them to open up with each other. It's the type of manga where you like the action but also the interactions going on between the characters. It quickly rose up to my ranks to my top 10 manga. The pacing isn't too slow or too fast but enough to keep you entertained! Definitely will not disappoint! Last but not least, the anime adaption has been confirmed so lookforward to that!!