Board Thread:Off-Topic Discussion/@comment-28574980-20180122202029/@comment-53539-20180429101929

Actually, the range in his V1 is smaller then V3, but due to the flexibility of V1 all 5 V1 vocals can get away with a lot of the things V2 and later engines can't. The five V1's really had small ranges compared to the V2's since they were more or less were recorded with not much more then a single octave. The better and improve V2 engine meant that cruder results show up more. V1 also didn't work the same as V2, while V2 put focus onto samples, V1 used them merely for reference and the engine did almost all the work.

Kaito's update isn't needed, there is little difference between V3 and V4's except the new style of recording the Japanese vocals. Also note, extending the vocal range also impacts the way the voice sounds as your adding more samples to extend the range. This is part why some studios are reluctant to mess around with their older established vocals. Just by adding one extra layer of sound to extend the vocal range, sure, makes the vocals stable, sure... But changes the overall result. So if you extend Kaito's range much further, he may not sound like Kaito at all, which CFM didn't want to do.

So yes, maybe Kaito could do with a voice extension but their more likely to do what their doing with Miku to him - slowly adding a few notes to a couple of voicebanks per update. However, he may get EVEC along with Meiko when they next update, who knows... Their Yamah's pair so we can't say how much CFM are allowed to do with them.

As for the others... I think you miss some notes;
 * Len is voiced by a female and can hit high notes for this reason. Note that all teenage males voiced by males often don't have the ability to hit quite as high notes as Len. He works on a soprano scale - which is the highest female vocal range.
 * Kiyoyteru can hit high notes, but can't actually go that high since he is male and is restricted. He is basically a tenor which makes him a high male.  He has a decent triple range, however, which allows him to handle the high range of his vocal range really and he has a lot of "lift" to his voice.
 * Gackpo is a low toned male, he can't hit high notes that well at all. He is a baritone which makes him a mid-tone male vocal. The highest he can go is Tenor, any higher and he starts to be more LQ.  This is actually true for a lot of male vocals including Tonio, Big Al and Bruno.