These are Yu & Rei, both minor roles. Yu is a cheerful female ghost, and is never usually seen in a bad mood. She is accompanied with her twin brother, Rei; they are collectively known as Yu & Rei. Yu makes puns and is constantly silly. While Rei is much more reserved and gloomy personality. This is a dual-role, and anyone who voices Yu has to voice Rei.

Yu's voice is meant to replicate the voice demonstrated Here
For Rei, use the same voice you have for Yu (no pun intended), and make it sound very gloomy and reserved. 

If you can't replicate the reference voice, you can make your own interpretation of Yu using the description below:
(These are for Yu)
- Cheerful & Bubbly
- Innocent
- Female