Read as English letters 'S-S-R'. From Japanese gacha-game tradition (originally スーパースーパーレア, Super Super Rare), heavily used across Chinese mobile titles like
原神 (Genshin Impact, where it's called '5
星'),
阴阳师 (Onmyoji), and
明日方舟 (Arknights). Rarity ladder typical: N → R → SR → SSR → UR / SSR+. Closely tied to
抽卡 (chōukǎ, gacha pull) and
氪金 economics.