Oh my god, that name is an amazing pun.
Younger princess -> sound princess
The Japanese word for sound is also pronounced "oto". So, a device which makes noise to help you be discreet...
But things that look like cognates with Japanese do exist. Notably そう ("sou") is pronounced the same as English "so" and means roughly the same thing, at least in phrases like "is that so?" and "Make it so, Number One."