It's not. But the author makes other VNs too, so it takes a lot of time for an update. I've been waiting for a new Hollow chapter for an incredible amount of time.
waht is the other VNs?
Hollow (free, others are paid)Blind Date (haven't played yet)MGUniverse (in Hollow universe)Fortune Favors (in Hollow universe)Lonely Lights (in Hollow universe)Eternity (in Hollow universe)New Hope Christmas SpecialNew Hope Unlimited