Tomioka Tessai was the pseudonym for a painter and calligrapher in imperial Japan. He is regarded as the last major artist in the Bunjinga tradition and one of the first major artists of the Nihonga style. His real name was Yusuke, which he later changed to Hyakuren.
As he meets the Riddles in 1844, he would've been approximately seven years old at the time. Despite that, he is seen with a mighty white beard. It's unclear if that is a fake, or if the Riddles somehow perceive how they will look as adults even if they are still kids when they meet them.
Tomioka's Father who appears in the episode, actually died in 1843, a year before the Riddles arrived, so his presence is spooky.
Brad says that Tomioka was born in eighteen-thirty-SEVEN, however some books say he was born in eighteen-thirty-SIX. For example this archive or page 185 of this book.
This better matches up with claims that Tomioka was seven years old in 1843 when his father died, which would make Tomioka approximately EIGHT when he met the Riddles the following year in 1844 (although in the show, his father apparently had not died the previous year... or he got better).