The fights in this manga are always short... but you can see exactly why in each of them.
Tarume made a strategy based on past events, procured the substances needed, then concocted a wild "poison" to deal with him, she even accounted for the possibility that telling Ozuno could lead to Kozumi knowing.
Kozumi's Ashura form was cool too, using JJK Sukuna as an example, having double of each limb and organ, except legs, gives him such an advantage in fighting and spell casting.
But I have to say... didn't think calling him a ghoul would be so on point... and... his "immortality" is kinda creative.
There are so many elements in there... ascendence through enlightenment, accumulating divine treasures through repeated voyages in the flow of time, consuming his own alternate selves after he groomed them into stupidity, and there is the "solvent and adhesive" he used.
IIRC, it was mentioned before it being a sacred treasure, and I think it has something to do with the "origin of humanity as grass" in this story... don't know if he stole it from a kami, or achieved it through study, but he must have tapped into the "primordial soup" that makes humans and refined it into that "substance"... cool.
I love how this story took well-known tropes and cliches, mixed them with Japanese mythology in an interesting way, and still gave a sprinkle of originality that is left not explained... like the Amatsus' true forms being organs, and how it plays into the true form of the other kami, the little hints of how science and magic mix here.
Truly amazingly crafted storytelling.