I'm looking for a novel where mc is a male and has a romance with his female teacher, it'll be best if action be in fantasy world (with magic and swords) or sci-fi (futuristic with guns etc)
Try this: Returning from the Immortal World http://www.novelupdates.com/series/returning-from-the-immortal-world/
http://www.novelupdates.com/series/great-demon-king/ http://www.novelupdates.com/series/romance-of-dragons-and-snakes/ the mc seems to have sentiments for his teacher, as it has romance tag, I bet the two will end up together http://www.novelupdates.com/series/zhanxian/