Hm. Searching around in English only gave me a few results for Takeda Sun/San/Zun, and they all pertained to his other work, "Aruite Ippo!!".
Small bunch of pictures by him on danbooru:http://danbooru.donmai.us/post/index?tags=takeda_sun
It doesn't help either that mangaupdates hasn't got any info on him. Aruite Ippo!! there cites him as Takeda Zun, which doesn't link to an info page.