My first ever voice acting experience was Jacob Chapmans "Fruits Basket Radio Drama", an audio adaptation of Natsuki Takaya's famous manga.
I got to voice one of the protagonist's best friends from 2011 to 2013 and it sparked an ongoing passion for voice acting within me.
The episodes have officially been taken down years ago but you can still listen to all of them on archive.org.
Fruits Basket Radio Drama (archive.org)