Bleach manga spoiler) Why didn't Ichigo need an Asauchi? - Quora
HD substitution wallpapers | Peakpx
Bleach: Ichigo's True Zanpakuto Makes No Sense
Ichigo's Two New Zangetsu's! Juha Bach and Hollow Ichigo – Bleach 542 | Daily Anime Art
Potential theory(might be entirely wrong): ichigo's appearance in the one shot is his true shinigami form and his appearance in the thousand year blood war arc was made by the zero division. :
Bleach: Ichigo's Final Zanpakuto, Explained
Ichigo Kurosaki - Wikipedia
Bleach 541 Manga Chapter Review "Ichigo's New Zanpakuto " ブリーチ - YouTube