
If I were the author I would have given rika an excuse like ,"guys I need to go to canteen or bathroom or need some air or have some work to do , so you guys carry on I'll be back(but not coming back till you shits close the damn bottle). I would have really done that If I was this manga's mangaka :')

the thing is he didnt have the time to do that, they said they would open it and afterwards immediately went to open the bottle. rika was immediately affected, so running vs trying to stop the bottle from opening wouldnt have worked very well. he wouldve still been affected regardless of if he came up with an excuse to leave

they said they'd open it a little and then he reacted by trying to stop them, i dont think before he said "guys dont open it." he just said "hey let's not..." with incomplete sentences. but yea, now that im re reading the scene he shouldve just left, but i dont think he wouldve been able to be that logical in a stressful situation like that

That aunt was one damn selfish aunt!!! He's foster parents did loved him & thought of him as their own but her aunt maybe inside didn't think of him that much but as a nobody when the new baby's news came! :'D I bet when she used to come to her sister's house she always tried reminding him more that he's nothing to them! :v
Thank you for the update! ~
Poor taehyun