Are we sure that Sage Mode Hashirama isn't just a super powerful Creation Rebirth? A that's why he has unlimited amounts of heal because of his enormous Chakra stored in the seal. :
Does the Naruto manga explain how Hashirama got sage mode? - Quora
Who would win in an only taijutsu fight, Naruto or Hashirama (with sage mode and without sage mode)? - Quora
THE FORGOTTEN SAGE MODE-ORIGINS OF HASHIRAMA'S SAGE TRANSFORMATION - YouTube
Hashirama sage mode | Naruto Amino
Hashirama Senju | Death Battle Fanon Wiki | Fandom
Naruto: How Hashirama Senju achieved Sage mode, explained
Naruto: How Hashirama Senju achieved Sage mode, explained
What kind of sage mode did Hashirama have? Also, what was his summoning animal? - Quora
Naruto Learns the Legendary Hashirama's Sage Mode and Use the Wood Style - Boruto - YouTube
who taught Hashirama senju sage mode?? | Anime Amino
gay ninjas is the same — hi sakura should've had wood style + sage mode...
Hashirama [sage mode] ver.woman //my artwork and I try to draw he like a woman😂 : r/Naruto
Naruto: How Hashirama Senju achieved Sage mode, explained