Stop!! Hibari-kun!

While both series are completely different plot wise, the characters and romance are definitely similar. Hibari is a lot like Lum in terms that she's madly in love with the main character, Kosaku (Lum being madly in love with Ataru). Not only that, Ataru and Kosaku share the same traits where they fall in love with any other girl versus their main love interest. Hibari and Kosaku live under the same roof and attend the same high school just like Lum and Ataru. Other similarities between others include: Hibari and Ryuunosuke (both hide their gender perspectives at school versus with people they know well) as well as other side characters who easily fall in love with Hibari or Lum. The humor is very slapstick, random, over the top while the romance can share great love stories not only between the main characters but others along the way. Urusei Yatsura and Hibari-kun are episodic and don't always stay on one plot. Both are entirely set in the 80s so you'll definitely see some 80s style outfits, music, reactions and historical features. If you liked one, you'll probably enjoy the other. read more 

The setting in these two series is very similiar. Guy goes to live with a family that has three daughters. Both of the series contain same kind of humour and even though Ranma ½ has more battling, they share the same kind of feeling. 

Both anime start with the same plot, that is a boy cross dresses as girl, the first few episodes of futarigurashi feels similar to stop hibari kun, well stop hibari kun is from 1982 and this is from 1998, but I definitely enjoyed both of them, stop hibari is not as ecchi as futarigurashi, and the main characters definitely look alike. 

One of the Character acts and dresses like a girl and they both hit on a particular boy. They will do whatever to make them theirs. Both very funny and interesting animes.  

Whacky yakuza comedies, need more of these. 

The main character is blonde as well as a trap who makes the other character very uncomfortable.