It's like vampire stories just needed to be triggered to start journey as sucking blood. Btw she was suicidal from the first it was not the younger brothers fault cause he never forced except manipulation I guess . He manipulated his elder brother Sai to be a blood bank for him ...and at the last panel the younger one made the elder one triggered I guess so. Btw except the younger bro jerking off to his elder brothers there's no romantic love between them .
It's like a torture manga ,rubbish from the very first left at ch 2 ... Scam(⊙…⊙
For me it would have been more relatable hadn't cut most of it out I'll have to the novel