Uchi No Otouto Maji: De Dekain Dakedo Mi Ni Konai Best

The story follows an older sister who discovers that her younger brother is surprisingly "well-endowed" (referring to height, build, or physical attributes). The title translates humorously to "My Little Brother is Really Big, But He Won't Show Me." The comedy stems from the sister's relentless curiosity and the brother's desperate attempts to maintain his privacy and dignity.

If you need a “proper report” for an assignment or forum, I recommend stating: uchi no otouto maji de dekain dakedo mi ni konai best