Incest isn't my thing, so I'll say this:
Maeda does not have a fetish, she just spoils her brother, but not romantically (The reason why will be explained in future updates).
Akira's position was already explained in Chapter 4 (More in deepth if you talk to her as [I].)
Mirai isn't a potential LI, so just cute scenes with her.
Nobume is not MC's cousin. (Which I think is obvious.)
And one more thing, there will be more LI's for both [R] and [I].