Hassel's Japanese name Hassaku (ハッサク) is based on hassaku oranges that originate from the Hiroshima prefecture in Japan.
(That's why the orange/tangerine emoji is used to represent him in the fandom side!)
Hassaku can also mean the 1st of August and the festivals celebrated during the month (not related to the abovementioned tangerine).
In Japanese, Hassel uses the first-person pronoun 小生 shousei.
Here is a Tumblr blog post that explains the meaning and usage of that pronoun, though it focuses on a completely
different character and franchise.
While canon characters do not appear in the TCG-based manga Let's Play the Pokémon Card Game!, there is a character loosely based on Hassel: a young boy named Kessaku.
Not Hassel, but his counterpart in the TCG manga, Kessaku.
Hassel was in the 93rd place of the 2023 yumejoshi's top 100 favorite character poll.
The pattern on Hassel's sweater vest is similar to the pattern on Arctibax's stomach.
Some fans have calculated that Hassel is about 192 cm tall.
Like the other trainer NPCs, Hassel has a unique idle animation of his own during battle, tapping his head.
During battle
While Hassel elegantly exclaims "The mighty dragon has been felled!" upon losing in battle, in the Japanese version he roars "DRAGOOON!"
He also does the same roar when Larry makes him angry in the League Club Room.
In the Japanese version, Poppy calls Hassel "ojichan" aka "uncle". For some reason in the English translation, this was translated into Grandpa Hassel.
(They are not related, if you're wondering).
The Go Fest 2025 exclusive pose for the trainer avatar in Pokémon GO is based on Hassel's pose in his character art.
Some fans have theorized that Hassel might be loosely inspired by Kinpachi-sensei from "Mr. Kinpachi in Class 3B", a famous television series in Japan.
Although you never see them because of his hair, Hassel does have ears on his 3D model.
