Hopefully not...The spoiler that i read said: "IN CHAPTER 95 STEFAN AND FRAN TRY TO GIVE EACH OTHER A HAND JOB" as sex education and the love interest is someone else. The couple are:"14yo NOBLE FRAN and 18yo MERCHANT/COMMONER TREIZE the confession happens at chapter 99 and sleeping together at 128(in the novel),and the oldest brother gets married that's what I got from the spoilers. So as far as I understood it the incest was only as far as hand job...? (Spoiler from :chaelattea, Anonymous, MagicalReader)
They don't get into a relationship, (older brother got married) there's a weird ass chapter where he teaches Fran to masturbate. The manga is a marked Shonen-ai so it will probably skip over it (I might check over the novel when it gets fully translated just in case). As they already skipped some things from the novel.
Nahhh bro, i thought it was with the "shounen ai" genre by mistake but after reading the spoiler... WHAT THE ACTUAL FUCK?
Wdym fran and his OLDER BROTHER literally have sex and just be into a relationship??? WHY??? HOW did come to be like this? I am terrified