pija_(pianiishimo)
Artist, NicoNico Douga video creator.
Nicknames: ピジャ (Pija), ピジャP (Pija-P) or ピアニッシモ (Pianissimo)
Circle name: PIANIISHIMO (even though the reading is ピアニッシモ / pianissimo, the artist always spells it in that way)
Site name: ゲーマーウォーズ (Gamer Wars)