Said it before ... it applies equally here, so saying it again:
A Cheating Scenario is NOT Supposed To Be THIS CUTE!
For all we know, Haruka might be open to sharing Tomo with Ririka ... on the other hand, if a certain picture is revealed, Tomo might be subjected to some kind of Girlfriend Inquisition.
Still, what a nice older sister. She writes everything her little sister does to her boyfriend as her 'warming up' to him or something similar, unaware that she may be attempting to...take him from her. And she even left them alone to go shopping by herself...! She's like a wingman to her sister but against herself. Also i kind of like how he set himself up by essentially pushing her against his boner when her sister called out to him... 'Bothering him/me/you', though. The phrase that all of them pretty much say at one point...Certainly an interesting word, isn't it? Because what she does to him doesn't really seem like a bother(to us readers anyway, I'd think), if anything, it makes things interesting. This release should have had this word in the title! By the way, I'm slightly disappointed that the older sister didn't get any loving in this release, but I'm quite happy with what we got. Also I love the artstyle, as expected of this artist, one might say. Great ending too. I'm sure you two will be getting alongj just fine...I'd certainly love to see you two 'getting along more' in any kind of sequel, and if possible you should also be 'getting along' with your sister as well.