Making box office records in Japan can be hard, as noted in this piece by the Hollywood Reporter, as you're dealing with both a very stagnant economy as well as a shrinking population. That said, 2010 saw the highest attendance at theaters since 1974 with a record $2.66 billion dollars made. And even more interesting is the shift that the domestic films rather than Hollywood films had their best year ever with more than half of the revenue coming from that. This marks the third year straight of this, something that hasn't happened often, which fits in with the way studios are attempting to make films that actually compete with Hollywood in terms of budget and special effects while using some very well known properties. Of course, Hollywood still has a huge hand on the market when you have films like Avatar, Alice in Wonderland and Toy Story hitting, but Japanese films held strong this year overall.
On the anime side, Ghibli's release of Arrietty went very well with $111 million made while the latest One Piece Film, which is noted as the only non-Toho domestic released film in 2010, made $58 million.
An interesting note is included in the Hollywood Reporter piece that in an effort to combat the falling population, Toho is going to experiment in certain markets with reducing ticket prices in the hopes of increasing overall attendance.