Did Tokito and Genya ever stand a chance against Kokushibou? They both got dealt with in a few seconds, yet they were the ones that lead Himejima and Sanemi to victory.
If Giyuu runs here, Muzan will kill Tanjirou, and then every remaining pillar one by one. Giyuu can't escape the Dimensional Infinity Fortress, so staying is actually the scenario in which he has the most chance of survival.
You have a point that staying is the best option, it's not like he knows where Iguro and Mitsuki are right now anyway so he could run, but where? But like you just said, Tokito and Genya never stood a chance....... and died trying. Which is exactly why I'm predicting Giyuu's death. I mean has barely able to scract Akaza with his broken sword, I'm sure he can fight and will stand his own, but in the end, just like Tokito and Genya, he will end up doing a big play that will end up severely injuring Muzan before Giyuu dies.
I mean if there are Giyuu fans out here then you guys really have just one hope. And that to put your faith in Iguro and Mitsuki to defeat UM4. QUICKLY! judging by their convo in this chapter, they've been stuck on the UM for who knows how long considering that 2 fights have gone by and nothing has ever happened to their fight tells you how stuck they are. I guess since I don't really know Iguro abilities I'm going to have to count on Mitsuri a bit here.
GL to Giyuu fans out there keep praying
