REFERENCE PICTURES ARE UNOFFICIAL. 

Rino is the male Neko Boy (cat-person) 

Rino's personality is more reserved than Kyla's. While Kyla would be the one to take risks first, Rino would more than likely just follow along with her lead. Rino is also the type who loves to read mystery novels and write poetry. 

Rino tries his best to keep his sister Kyla out of trouble but sometimes her curiosity gets the better of her. He is more likely to follow the rules to avoid punishment for both him and his sister, even if he knows that the rules are quite questionable. 

Rino and Kyla are supposed to be 12 years old so I will be okay with having a female audition for this role given it sounds like an adolescent boy.  Given his personality, he should sound kind of meek and unsure of himself. 

If you'd like a voice sample to compare or try to be similar to, I'd have to say Dan Green's version of YOUNG yugi-muto (Yu-Gi-Oh!) might be a good start. https://www.behindthevoiceactors.com/movies/Yu-Gi-Oh-The-Dark-Side-of-Dimensions/Yugi-Muto/ 

NOTE: Kyla is pronnounced as 'Kai-La" & 'Neko' is the actual Japanese word for cat- it's pronounced like the 'Necco' Wafer Candy Company. (hopefully that's an easy way to remember!)