This has always been a bit of a mystery...One possibility is that it's a NC.

A bit of it is used in the OP, but not in its entirety, so I don't think it would be someone from there, but its not impossible.

Otherwise: could be Habara, as he was no stranger to doing bank work like this for the studio, (he is credited but I still think that might be for the special Avan, but he's also gone NC before for stuff like this too).

Could also be Takuya Matsumura as he was undocumented for a long time and the timing does remind me of him a bit.