Hozuki-san Chi no Aneki - Vol. 2 Ch. 18

[MangaDex]

 

[BakedBanana]

The sister is pretty unlikable, I would say MC should just abandon ship and go for the seaweed girl but his chances are slim with how much the sister meddles.

 

[DementisXYZ]

... dude needs to move out.

 

[matmatpog1]

Stupid aneki meddling in my mizuno and gorou ship, now the ships fucking blown up