Manga?

I don’t think that’s a manga....they r voidloids...I think that’s how I spell em

Vocaloids

Not a manga, xD It's Vocaloids. Robots (kinda, I don't know the right word for it) who sing.

There are mangas with the people present but yes they are mostly computer synthesized and made-up-mascot-for-the-voices singers. Names such as Hatsune Miku, Kaito, Len and Lin Kagamine, etc. Mangas would have a name like "Hatsune Mix" or something similar. If you like their designs there are music videos of them dancing and singing and stuff.