- This article is about Gohan's tutor. For Emperor Pilaf's minion, see Shu.
When Chi-Chi is not in Gohan's room, Mr. Shu spends his time whipping Gohan, insulting his work for any slight mistake, and calling Goku names. Later, Gohan has a dream where Goku returns, but it is really Frieza in disguise. Gohan attacks Frieza, but when he wakes up, he sees it is really Mr. Shu he is attacking.
Mr. Shu yells at Gohan and further insults Goku, calling him a brainless brute. When Gohan defends Goku, Mr. Shu attempts to whip him again, but Gohan effortlessly catches the whip, angrily states, "For your information, Mr. Shu, my father is not a brute. He's a great man. Is that clear?", and then crushes the end of the whip to powder, leading to a terrified Mr. Shu calling Chi-Chi and proceeding to tell her his end of the story, making Gohan sound like the bad guy.
After Chi-Chi chastises Gohan, Mr. Shu proceeds to state that this is due to the father's influence and ultimately pushes Chi-Chi too far when he states that Goku abandoned them, calls him worthless, and whips Gohan across the face hard enough to draw blood right in front of her. While he is laughing at his own words, an outraged Chi-Chi literally throws Mr. Shu out of the house through an open window. When he yells at her and threatens her from outside, she proceeds to jump out the window herself and chase him away, warning him never to come back.
While Mr. Shu does not appear again after this, Ox-King is later told the story about how his daughter threw him out of the house, much to his amusement.
Presumably he is killed along with most of the Earth's population during the Majin Buu conflict (most likely by Super Buu's Human Extinction Attack or when Kid Buu blew up the Earth) provided he did not die before that. If his death was caused by Buu, then due to the fact that he was a bad person it is unlikely he was resurrected by Porunga.
- Mr. Shu's Japanese name, Sai'aku, is translated to "The Worst Teacher": Sai is written with the kanji for "disaster", aku with the kanji for "evil" and, together, sai-aku is a homonym for "the worst" (最悪). Shū (Zhou in Chinese) is an actual Chinese family name.
- Mr. Shu resembles Pamput, a fighter that entered the 22nd World Martial Arts Tournament, because they both have similar afros and have similar eyes. But Mr. Shu has a mustache while Pamput does not.
- Mr. Shu says at one point "Oh my foot is not!" which could be a pun of his name since his name is a homophone of the word "shoe".
- Before Chi-Chi throws Mr. Shu out of the window in the original Japanese version, Mr. Shu insults Gohan by saying that he is harder to teach than a "mere monkey" and that he has "no real potential". However, in the Funimation dub, he instead insults Goku calling him a "worthless father" for unknown reasons.