Is it possible?
Is it possible to add foreign letters or kanji to your name?
Is it possible to add foreign letters or kanji to your name?
You can find the full list here; https://support.riotgames.com/hc/en-us/articles/201752814-Summoner-Name-FAQ#h1q4
Sometimes you'll see a player with characters not on the list, but that's because they had the name before Riot added these restrictions.