Are Denzi's pixelart assets free to use?

Are Denzi's pixelart assets free to use?

I'm not an english or Japanese native speaker and just wanted to make sure lol. Are all Denzi's assets free to use? Here: www3.wind.ne.jp/DENZI/diary/

I just need to make sure, and to avoid copyright issues. I'm mostly a programmer and currently working on a small RPG game made with Java for educational purposes and to test my OOP skills. I might end up publishing it on itch.io (for free)