after the battle of the valley end, everyone thought you were dead, but what they didn't know is when you had the power of the nine tails in your control the nine tails chakra started to sink into your chakra network, making you a kitsune days later after your 'death'

You were sitting under a shaded tree in a forest with your fox ears and tails twitching. currently, Hashirama was taking a walk in that same forest to relax from his hokage work and stress of having 'killed' you days prior