As a harem manga, Umi no Misaki and Hare-Kon are basically in the same vein. I label them "true harem manga" where the main protagonist does not shy away from the harem idea itself, instead he embraces it and actually follows through without displaying much favoritism toward a certain girl. The setting is also quite similar; due to different circumstances, they are living together under one roof. If you like these kind of elements in your harem manga, look no further, these two are for you.
Well, if you are looking for a harem comedy beyond the normal boring shounen setup, well hopefully one of these will suit you. Hare-kon, while still fairly new it has the original premise of a girl who is invited to become the third wife, and even though umi no misaki have a very conventional setup, it have a very unconventional execution and is way beyond most harem comedy tagged stuff.
Both manga involve a guy trying to sort out his romantic feelings for multiple women at the same time. In both cases, a harem develops around the male lead, but without all of the usual "harem antics". Instead, the focus of each is on how the man comes to know--and love--the women around him, and why they love him back in turn. The difference is that UmN is more of a slice-of-life and has a mystical quality to it, where Honeymoon Salad is much more grounded in the doldrums and drama of real life.
Similar genre (comedy,romance,harem)
protagonist living with various girls/sisters
Both focuses on romance
main heroine kind of tsundere
gives similar vibe
Umi no misaki has kind of supernatural touch.
Pastel is more of a shounen
umi no misaki has a better plot
Both feature 3 likable heroines. Though the mixture of personalities is different, you'll definitely find a preference in one of them.
Both start off fairly slowly, but have a magic in them where characters begin to grow on you as you read on through the story, and before you know it - you'll be entirely immersed.
If you get sick of one, at least try soldier through 25 chapters worth before dropping it (because that's where Ichigo 100% began to pick up, I dunno when Umi no Misaki got interesting for me, just did).
These two series, both by the same author, definetly share some similar themes and character designs. Ai Yori Aoshi is a love story wrapped in a harem comedy, and so far Umi no Misaki is a supernatural(?) mystery story wrapped in a harem comedy, both with a little tasteful fan-service.
although the plot's are totally different in these, they both give off the same sort of feel. in both of these, the main character has a variety of girls that want to be with him and do so by going behind the other girls backs. all characters are likable and they both have parts in them that make you laugh out loud...