He is a fan of Halloween. His wife is unknown and he has no kids.
He turns his yard into a theme park with a giant balloon spider, mummies, skeletons, and bedsheet ghosts. He loves kids and is always jovial. During Halloween night, Mr. Chu gives candies to a line of trick-or-treaters, disguised as Frankenstein. When decorations and masks are brought to life by Slappy with Tesla Tower, Chu helps Sarah, her brother and Sam to hide them in his house.
He disguises teens as monsters so they go out on the streets unnoticed and go to the Tesla Tower.
When Halloween monsters are sucked by Sarah's opening book on the tower, Chu congratulates them, from home. It is unclear whether he remembers events that happened because Stine stated that all affected people will have forgotten everything. The last time we sees Mr. Chu is at Christmas.
He made a sled with a remotely controlled reindeer just in case. He shows it to Sarah before saying goodbye to her.