The final member of the Four Directions Slaughter Wave was Akainu, and he was likely the most brutal of all. Even though the others killed, the deaths were usually quick and served a purpose with not much pain.
However, who can be instantly killed by lava? It did not have any explosive effect and was mostly burning and dissolving, so one touch would be cooked to death while screaming in sheer agony.
Akainu's eyes flashed with a special emotion. He seemed to almost see himself fighting against a bunch of filthy pirates and having a great time suppressing them with cruelty.
The poor civilians before him became like those pirates in his eyes and his movements became more active and filled with excitement. He even found himself shouting with joy with each one he killed.
Akainu was distracted by a noise and happened to see his younger brother Sanji in the air dropping down kicks full of flames.