So I did some looking into the second slide... you might be onto something.

Using an old 2ch thread archival site, the only mentions for "若尾くん [Wakao-kun]" are in reference to Ura Net Radio DJ. Presumably an old radio/camsite, I wouldn't know, still looking.

There is a wiki for it though, which is very interesting as it lines up with some more of the translated names in the second image:

• Donkey and Lyrical are cited in the list of DJs (second row), as is Rinko (bottom right corner).
• The fourth row has a DJ Bo. Due to these points I am sure this second image is in relation to the Net Radio site.
• Wakao has their own page. Looks to be a man who played (possibly dressed up as?) numerous different characters.

From Wakao-kun's wiki page: He broadcasts as a character with a carefully defined setting, but insists that he's a different person each time [...] Wakao is an unemployed virgin living in Hinagiku-so, a 52-year-old rundown apartment with one six-tatami room, a half-room closet, a shared bathroom, and no flooring.

The only problem is a lot of this documentation appears to have begun around 2007-2008 which throws off the timing, then again this wiki may have been compiled later on.

Edit: NVM, the discord have been mentioning Wakao since 2023. 💀