According to the Official Japari Park Field Guide, she can hear out of both!
Her animal parts are comprised of “Kemonoplasm”, which is a substance that takes the form of external, yet not entirely vestigial, appendages such as a tail and ears.
All these parts are fully functional, but are merely ‘extra’ parts for a Friend.
According to this guide, Friends, if they so wish, can remove their animalistic features to become truly human, if they wish!
Therefore, to summarize the answer to your question, this neko girl in particular would use both ears to listen, but only the human ones are her true ones; the Serval Cat set of ears are merely for enhanced hunter’s hearing!
Is this implying the Friends’ animal bits are detachable cybernetic enhancements
never make a suicide joke again. yes this includes “i wanna die” as a figure of speech. swear off of it. actually make an effort to change how you think about things.
find something to compliment someone for at least 4 times a day. notice the little things about the world that make you happy, and use that to make other people happy.
talk to people. initiate conversation as often as you possibly can. keep your mind busy and you wont have to worry anymore
picture the bad intrusive thoughts in youe head as an edgy 13 year old and tell them to go be emo somewhere else
if someone makes you feel bad most of the time, stop talking to them. making yourself hang out with people who drain you is self harm. stop it.