“Oshi” is a term which comes from Japanese idol culture. Basically, it’s the person a fan stans the most. See also virtual youtuber VTuber Sensei’s Slang Guide Yumemipi’s Oshi Terms 101: A Guide Blueshiba’s J-pop terminology NILS blogpost about “Oshi” net-idols wiki terms TAIGA KARA FAIYA blogpost for terminology Unseen Japan’s blogpost on What makes Japanese Idol Culture Unique?