I think it's just one of the standard JP voice synthesisers available. I know I've heard almost exactly the same one on other Youtube videos using text-to-speech for Japanese.
So.. I know many people can read hiragana, but it is a very annoying habit of people who know a bit of Japanese to post un-transliterated Japanese text on an English language forum. For someone who doesn’t know Japanese your post reads ‘IIRC it’s a popular TTS character called ??NOT?FOR??YOU??’ - it communicates no information.
Writing ‘a popular TTS character called ずんだもん (zundamon)’ takes you very little time and gives readers a little more to work with, and which they can use to Google English language resources on the subject if they are interested.
Copy-pasting "ずんだもん" into Google gives you everything you want with the sidebar info, copy pasting "zundamon" into Google gives the same Wikipedia link on the sidebar. "Popular TTS character called" is enough to imply that what follows is the name, that you can then search.
Try to be more generous with your change requests - not everyone has enough time to fix every bug in their comment.
The strongest plausible interpretation is that when keywords are in another language, it is best to give the original language keyword rather than the anglecised/romanised version (which is so often incorrect e.g. Huawei's Tau[1]). It is also plausible that English is their second language.
As an addendum: Japanese isn't as all-in on pitch having semantics as Chinese, but pitch is very important. Words have "pitch accent" rather than "stress" the way English has, and overall pitch is strongly politeness-coded.
Speaking higher is politer, and noticeably dropping your pitch is threatening. You probably would pitch-up when speaking to your boss, and people working in shops or restaurants nearly sing welcome/thank you for coming type things.
Don't be smartass. My question was how to change pitch? Most people can't change their pitch unless they have been trained. I can't speak with the pitch of child or woman. Neither are most people.
Comparing our culture to others, women in the U.S. are raised to do much the same. Ask anyone woman constantly misgendered for not having a high-pitched woman’s speaking tone (e.g. pacific islanders) and they’ll confirm. Best not throw stones from glass houses.
Sure, I've been here for almost 20 years. It doesn't change a fact it sounds stupid. I asked two colleagues from Japan and they both agreed this probably wasn't done by a japanese person.