The first Headless I encountered in Sekiro. I was seeing enough progress and understanding what was being asked of me just enough to be stubborn as hell and kept trying to fight it head on, without having any knowledge yet of any helpful items that make the fight less rage-enducing.
Outside of Fromsoft, my NG+ encounter with the green swamp monster thing in Lies of P seemed SO much harder than the first time. So I'm not sure if this boss is considered easy or hard, but I didn't consider it to be very hard going in for a second time and got quite stuck for a while...
I've only attempted it once and can't remember much of it except for those fucking tunnels being the reason I gave up also