The main issue with Japan's position in WWI is that they were torn between Germany and Great Britain. Japan had developed a close relationship with both powers as part of its post-1868 modernization, and public sentiment regarding both was very good. The decision to join the Entente against Germany ultimately had to come down to calculation. The Anglo-Japanese Alliance was a vital part of Japan's security arrangement. Something that, as much favorable Japanese sentiment as there was, it didn't share with Germany and it didn't want to threaten. Further, Germany's Pacific holdings were the easiest to attack, making the choice of sheer manpower figures an obvious one. Finally, Japan had labored at great length to put forth the image that it was a developed nation with modern and progressive political institutions worthy of inclusion in the Western "club". As the Entente powers (specifically France and Great Britain) nominally possessed greater levels of democracy than those of the CP, Japan saw more to gain in international prestige by allying itself with them. Systemic Realism at its finest.
In order for this situation to be different, I would say the most likely scenario is for Great Britain to also be a member of the Central Powers. In such a scenario, with its two closest allies both in the same camp, Japan's allegiance more naturally follows suit, with less room for calculation. Another possibility is that of Britain's neutrality in the conflict, but that is less likely on the whole, as if Japan were to join the CP only to have Britain join the Entente later, it would put Japan in a compromising and unenviable position. Alternately, one could push for a much earlier POD and remove the Anglo-Japanese pact from the equation entirely, replacing it with further ties to Germany. This however would likely leave the IJN, really the linchpin of Japan's military projection, in a less powerful state than in OTL, influencing their ability to actually wage the conflict.