Yoon had been pushing for it, yes; the agreements (as in, concrete steps having been taken) were announced bilaterally so I don't think that none of it was Kishida, especially as this happened extremely close to Kishida's announcement regarding Japan's defense budget. Either way, my original response will be edited to reflect this.

He has: agrred to Improved relations, begin lifting trade restrictions placed by previous administrations, help increase military cooperation between Japan, South Korea, and the United States, including overseeing the first military drills held trilaterally with all three countries, and to share all military intelligence bilaterally with South Korea.

Kishida already recently announced a massive $5.5 billion in additional aid, which would immediately make Japan one of the top contributors as far as money is concerned, and it wasn't prompted by a request from Zelenskyy.

Japan has always maintained strong support for Ukraine's sovereignty, and has levied major sanctions against Russia (though they haven't sanctioned a joint energy project in the Sakhalin Islands, for complicated reasons).

Hell, the Saitama Super Arena, Japan's largest indoor sports/concert venue (and it is massive) has been lit with the colors of the Ukraine flag for almost all of the last year, which is a pretty good indicator of public opinion regarding the war.