Kagamine Rin and Len have powerful and energetic vocals, and have been allowed to sing many songs. For the NT version, we considered the best voice quality and singing style to best suit Rin and Len as the default, and designed it so that Automatic Control and Vocal Morphing (a function that mixes two DB voices, similar to cross synthesis in VOCALOID) would allow for good dynamics.
I think the twin singers will be able to match the inspiration of users by adding tempo changes and singing in tricky ways, so please enjoy it. A free trial version is also in preparation!