2M × 4 banks × 16 bits SDRAM
https://www.winbond.com/resource-files/da00-w9812g6khc1.pdf
NAND Flash, custom Yamaha package based on the copyright info
64Mb parallel NOR Flash
http://www.cypress.com/part/s29gl064s70tfi020
Multi-purpose Yamaha sound processor
This is actually a relatively generic MIDI module, unsure if it's also the Vocaloid-on-a-chip implementation, but there's nothing else on the device.
Dolby DTS-capable floating-point DSP
Bluetooth chipset