Hendry is an older nekomimi man who used to work in the music industry.  She is also the Father of Rachel.  If you remember from day 3 Rachel doesn't have the best relationship with her Dad.  So he's a very overprotective dad worried about Rachel's well being.  She's going into a solo career and it worries her dad (Hendry) since he has experience in the music industry and knows what it's like.   He is definitely the oldest of all the characters in the game.  His age isn't stated but I'd put him around the 50-60 year old range.  So he's between middle-aged and senior.  To sum him up he's an older dad type character who loves his daughter but is unable to communicate with her and is loving but overprotective.

For his voice, just a more mature father like voice.  I feel like he'd have a soft but mature voice.  Like he's a loving father but since he's trying to repair his relationship with Rachel he'd have a bit of desperation when talking to her.  So to recap his voice would sound like an older man's voice, more mature.  But add a lil softness because he is a loving dad.  Again feel free to give your own interpretations and maybe I'll end up liking it more.