NIER REPLICANT ENDING C
Reload your ‘Ending B’ saved game file. The game restarts at the halfway point again. For the next three endings, you need all 33 weapons, so first collect all missing weapons.
Related: Nier Replicant weapons guide
Visit a save point at the top of Old Shrine and save the game, right before the final boss fight. Here shades have taken control of Kaine and your final boss fight is with Kaine. For ‘Ending C’ select to kill Kaine and free her from her burden.