Wide-coverage resources for lexicalized grammars have been obtained by converting the existing treebanks into collections of derivations. Additional annotations to the source treebank can be used to improve these derivations. A treebank annotation called the NTT treebank was used for this paper to improve a CCGbank for Japanese. The source treebank of the CCGbank itself is created by automatically converting chunk-dependencies, but the CCGbank contains errors caused by noisier phrase structures and a lack of linguistic information, which is difficult to represent in chunk-dependency. The NTT treebank provides cleaner trees and functional and semantic information, e.g., coordinations and predicate-argument structures. The effect of the improvement process is empirically evaluated in terms of the changes in the dependency relations extracted from the resulting derivations.