Remember all the optional boss guides we did in the past for From Software games, because they all have optional bosses? This is kind of like that for Sekiro: Shadows Die Twice.
Location spoilers below, as well as the name of the optional bosses. Everything else is kept vague.
Read more…
Source : https://www.destructoid.com/sekiro-guide-how-to-find-the-main-optional-hidden-boss-for-the-trophy-achievement-547577.phtml