Krillin & Muten Roshi

At first, I really didn't think there was much to say in a relationship of Roshi and Krillin. It wasn't until I saw an episode in later Dragonballl Z almost near the end of the anime did I realize there is a decent one to at least point out. Krillin is simply one of the students that Roshi first fights against as 'Jackie Chun' and compliments on how well Krillin did in the 22nd World Martial Arts Tournament and Roshi gets involved to fight against his pupils so they would not 'slack in their training.' I think Roshi over looks Krillin as a son and/or mentor sort of way, because he cries out when Krillin charges against Majin Buu, he cries out "Oh no!" (English). Krillin, on the other hand, attempts to help Roshi from getting injured by some falling roof pieces just a few episodes earlier caused by Majin Buu.

In Japanese in an episode of Dragonball, Muten Roshi states that both Goku and Krillin were very talented, hince furthering Roshi does care a bit more maybe than as the role of a mentor for Krillin (and Goku of course).

Trivia: The original Japanese voice actor of Master Roshi, Kohei Miyauchi/Takayuki Miyauchi, last line before the voice actor passed away was in Episode 260, the exact episode where Krillin and everyone are eaten on Kami's Lookout. His final line was "Kuririn!" before the Turtle Hermit was also turned into chocolate shortly later.