I like the "free" part best.
I've been working on building my tsume database at http://japanesechess.org. Now I have hundreds of shogi mating problems of my own creation entered. A lot of people may not realize how many features the tsume database has. Not only are there hundreds of tsume puzzles to solve, but you can filter on search criteria, view them in random orders, change the board view to kanji, western, or other piece styles, and you can remove the label that tells you how many moves are required to mate the king.
|This is one of the hundreds of tsume found in my free online tsume collection.|