Harry Takayama (played by Nathan Nishiguchi in Full House, and Michael Sun Lee in Fuller House) is the first on-screen friend of Stephanie Tanner, first appearing in the season two episode, "D.J.'s Very First Horse." His last appearance is in the season three episode "Nerd for a Day," and he is mentioned one last time in the season three finale, "Our Very First Telethon."
Harry is a nice, easygoing kid, though he does appear to be easily influenced by his peers. He does not seem to be very good at mathematics, as he mentions he is ready to drop out of school and become a Boy Scout over his frustration with grasping the concept of subtraction. He is a good friend to Stephanie, and is a welcome guest at the Tanner House.
Harry and Stephanie are good friends. He would usually call Stephanie "Chief," and she calls him her boyfriend – believing it only meant a boy who is her friend. This leads to a pretend wedding in the episode "Middle Age Crazy," in which he dumps her when he finds out his mom is making meatloaf.
In "Pal Joey" he has a crush on D.J., and as a result Stephanie becomes jealous (although they work things out with some help from Jesse).
Ironically, given his difficulties with mathematics as a child, Harry studies accounting in college and becomes a CPA (Certified Public Accountant). Additionally, it is revealed that one of his clients is Jesse. In "War of the Roses," Stephanie mentions to Becky that every few years (since Full House) Harry had done something crazy to try and start dating her, but that she had never given him a shot.
Harry makes an appearance in episode nine of season one. After not hearing back from Stephanie in response to the wedding invitation he sent her (which is among the items Cosmo had stashed under Max's bed), he sends her a text message and later drops by to see her in person. Becky and the girls still believe he has a crush on Stephanie, and may have been the one who sent all the flowers. After Becky's interrogation rules him out, Harry tells Stephanie that he is getting married "for real" this time and invites her to the wedding.
Harry is the first recurring character from Full House to be recast with a different actor in the spin-off series (the second being Nelson Burkhard)