Unlike static memes, this phrase includes a timestamp. You rarely see "No Otouto" without the year attached. Why?
Because the original joke is contextually dead. In 2024 or 2025, new anime fans watching Osamake for the first time won't hear the mishearing as clearly, because streaming audio codecs have improved, or because they are reading subtitles that correct the grammar.
Thus, adding "2021" serves a specific internet function: no otouto maji de dekain dakedo 2021
Once the mishearing went viral on /r/animemes and Twitter (X) in May 2021, the community mutated it into various formats.
Episode 2 of Osamake, which aired in April 2021, features a high-intensity argument between the protagonist, Sueharu Maru, and the rival heroine, Kuroha Shida. In a moment of emotional distress, Kuroha screams a line about her own little brother. Unlike static memes, this phrase includes a timestamp
The actual Japanese script is something akin to: "Otouto no koto, maji de dekai tte iu no dakedo!" (I’m saying my little brother’s thing is seriously huge, but...)
However, due to two factors—rapid-fire voice acting by Inori Minase (Kuroha) and the audio compression of streaming services—fans heard something else entirely. Because the original joke is contextually dead
What they heard was: "No. Otouto. Maji de dekain dakedo."
The ‘no’ particle detached from ‘otouto’ and attached itself to the front. The 'tsu' sound dropped. The meme was born.
The phonotactics of English speakers saying "No Otouto" is hilarious. It requires you to tap your tongue on your teeth twice in rapid succession. It sounds like a malfunctioning Mario.