Edu Da Shixiong Qiusheng Zhinan

Jiang Chen, master of fanfiction, transmigrates into a book and becomes the senior brother of the protagonist, Wen Lingyun. It's alright! This senior brother is just a villainous supporting character, betrayed Wen Lingyun, and died a tragic death... But why! The book he transmigrated into isn't even the original novel, but a lewd fanfiction he drew himself, complete with all the pixelated details?

(Source: Bilibili, translated)