We've completed the operation verification on macOS 15 Sequoia with following products.
The products listed below are now supported.

VOCALOID6 : ver 6.4.3 or later
VOCALO CHANGER PLUGIN : ver 1.2.1 or later
VOCALOID5 : ver 5.7.2 or later

We've found some problems with VOCALOID4.5 Editor for Cubase and lower versions.
These products are not supported on macOS 14 Sonoma and macOS 15 Sequoia.
Thanks for your understanding.