Mastered UI Kostas

Mastered Ultra Instinct Kostas (birthday: June 28), or simply known as Mastered UI Kostas, MUI Kostas, MUIK, or just Kostas, is a Greek YouTuber whose contents involves his gameplays of Sonic.Exe fan games. His current mascot is a white hedgehog with reality-warping superpowers.
==History==
Kostas joined YouTube in 2016 with the name Super Kostas the Hedgehog. He did not upload his first video until 2017, where he uploaded his first video about JaizKoys' Nightmare Beginning gameplays. He also played the sequel of the game called Continued Nightmare. Besides those, Kostas also uploaded videos about other Sonic.Exe fan games such as the Spirits of Hell and Blood Screams series.
Kostas's contents changed over time due to his fluency in English and skills at animations. He also decided to change the old YouTube thumbnails to satisfy his liking.
==Hacking==
Kostas' channel was hacked on March 3rd, 2022. His channel was deleted for "violating the terms of service." Kostas managed to get his channel back. However, and currently Inactive on Youtube but still is active on his other social media.
==Trivia==
*JaizKoys considered Kostas to be his brother due to multiple collaborations. Coincidentally, both of them share the same birth date.
*Kostas has a strong dislike for his past self due to embarrassment. He also used to hate the character Sark from the Nightmare series.
==References==
Category:Gaming YouTubers
Category:Greek YouTubers
Category:Users who joined in 2016