This is Strich, a tall and quiet student
Strich is the taller of Groose's two lackeys, constantly standing beside him or flanking him. Motivations for sticking by Groose, and other aspects of his character are a mystery. It could be that Strich is a quieter, calmer individual than Groose or Cawlin. Stritch is also a very serious bug-maniac. He can be found in the Lumpy Pumpkin on the second level where he expresses his love for these creepy-crawlies. If Link visits his room at night, Strich will enthusiastically purchase bugs from Link for a reasonable price. Strangely enough, he is away from his bully friends. When there, he acts somewhat kind towards Link, suggesting that maybe he is not the real meanie that a lot of people in Skyloft think he is.
After completing the Fire Sanctuary, Strich can be found on an island named "Bug Rock" in the Thunderhead. On "Bug Rock", or "Bug Heaven", he offers a mini-game in which Link has to catch all the bugs he tells him to catch. Later, he appears in a side quest "Beedle's Lost Beetle," after completing the sixth dungeon, and freeing Levias. By waking up on Beedle's Island, (By sleeping on his bed on his airship) he will tell Link he lost his beetle. By going to "Bug Rock", Strich will tell Link he found a rare beetle. After explaining that it is not his, he will tell Link he will only give it up if Link wins his mini-game. After winning, Link can give it to Beedle and gain five Gratitude Crystals.