Given the fact that Hidan’s head is attached to the rest of his body only through some threads, it would be very easy for Neji to blast Hidan’s head off of his body with an Air Palm, giving him an easy victory. This is realistically possible given that Neji was able to send someone as heavy as Kisame, who weighs about 83 kilograms. So knocking a barely attached head off would be no problem
Of course, Air Palm is unavoidable for those who can’t sense it or see it, as it’s not only extremely fast, but also invisible to the common eye. And given how rash Hidan is in battle due to his arrogance, he’d most likely try and tank any attacks used against him, as this is what he commonly does.
Hidan’s main weapon, this is what is used to extract small amounts of blood from his opponents. There are several ways for this to be countered. First off, if Neji shrouds himself in a chakra cloak, it will reduce the chances of the scythe from making contact with his body. Neji can also use chakra to destabilize and control the momentum of the scythe, allowing for him to avoid any actual hits.
Reacting to the Scythe’s speed should not be an issue for Neji, as both Hinata [when observing Obito’s transformation into Juubito] and Neji [When observing Lee’s overwhelming speed in 5th gate] have shown that the Byakugan is capable of tracking extremely fast activities with ease.
And while their foot speed may not be the best out there, their hand speed is extraordinarily fast, as demonstrated through the ability to strike 64 teeny tiny chakra points with precision in a second or two and as demonstrated through the ability to create shock ways powerful enough to send the Juubi’s tail or Kisame himself flying simply by thrusting their arms forward at alarmingly fast speeds.
If it comes down to close quarters, again, as mentioned above, Neji can destabilize and slow down attacks with chakra, and given his extremely fast arm speed, Hidan will not have it easy.
If Neji feels that he is being threatened or is unable to block an attack properly, abilities like Divine Revolution, Chakra cloaks or One Blow Body would come in very useful in blocking and repelling Hidan’s slashes, while simultaneously leaving him open for an attack.
