Kasane Teto (or Teto for short) Is a voicebank used in vocal synthesis programs akin to the VOCALOID program. Although not an official vocaloid herself she has an UTAU and SynthisizerV Voicebank. For more information please visit https://kasaneteto.jp/ The 41 is a reference to her birthday (April 1st, because she was originally an April Fools joke to prank VOCALOID fans into thinking a new voicebank was coming out)
Can you tell i like vocaloid