Normally I don’t like sudden backstories before someone faces their apparent death when it's sprung on a character who didn’t have much of a presence. For Kakyoin however, I have no qualms. He was written to be underspoken, yet despite being quiet, he had many sides to him that we got to see through the journey. It came off, not as if he was under written, but rather that until we saw first hand what was going on in his head, we wouldn’t get to know it. Not his past of feeling isolated; quelled by the Joestar gang showing us why he cared for them so much, nor his personal motivation to fight Dio and right the weaknesses that haunt him. He was able to make Hierophant Green invisible like it was in his past but this time for his friends. This all really reminds me of the One Piece character Chopper and his transformation.
That said, he forced Dio to use his power and we saw it from his perspective as he froze time, presumably in the premises that he can do such, and jumped to puncture a hole in Kakyoin’s chest. He must have known this was a potential sacrifice as they didn’t know what Dio was capable of. But he got some more information this way and he did actually land a hit, go Kakyoin!!
To talk on non Kakyoin related subjects, I was hoping the dynamic nature of the three sided chase would merge in a greater way than “making it just on time to see your friend lose” but as long as what we get is good I can’t complain. That and to speak completely out of tone, I keep wanting to mention that Dio and the World look like giant pieces of cheese in the colored version and Dio’s elf shoes and cape really top it off.