I'm surprised to see how there's only 1 vote "Yes" and one vote "No" for the Yandere tag. If anyone ends up reading this series, please make sure to vote yes on that tag.
Anyway, here we have an episodic romcom with an older sister in love with her younger brother, except it involves intense jealousy when he's around other girls, stealing his unwashed clothes, trying to turn situations into a perverse fantasy between them, wacky shenanigans, etc. etc. The childhood friend has a similar persona, yet is also a tsundere about it when we meet her. So for having those two as the female leads,
along with a side character that suddenly becomes a yandere for another side character,
it most definitely deserves that Yandere tag I mentioned. The younger brother is thick-headed like most of the typical male leads with female characters in love with him, yet it's sometimes successful in making some jokes out of it.
As a comedy, the jokes are most likely your deciding factor for the series. They usually involve characters having over-the-top reactions to simple situations they may find themselves in, characters talking about sexual innuendos/fantasies, or some "intense" violence and swearing at each other. Not much else to say in that department...
If there's one thing I'll give it a good amount of credit for though, it'll have to be two separate chapters that give a bit of background as for how the female leads became who they are in the series. Most comedies/romcoms I've seen never bother to take a look at a character's backstory, but when this series does that, it surprisingly plays it out quite seriously, without giving us any jokes (or maybe just one by the end of the chapter...). It's in no way emotionally deep, yet I find it nice to add a bit more variety to the overall series.
HOLY SHITE!
Update (12/15/15):
I really, really, really like this series to a certain extent, but MY GOD was I taken by surprise by the recent chapters (39-43). Basically, we have the sister put in a situation where it's flat out stated that she'll get raped unless Bro can save her in time. It's also blatantly stated how it's trying to pull a "brave knight saving the princess" act, and jeez was it really hitting you over the head with the whole "power of love conquers all" nonsense. I'll still be following the series despite this bizarre pile of heavy drama that was thrown in and then blown over immediately, but I just hope it won't continue pulling crazy shit like that down the line...