only CCP says it fought jap.

The fact is GMD killed more Japs than CCP did. They both did not use all their efforts in the war in the begining. The worst one is Zhang Xueliang. He did not fight at all and let Japs in. His conduct had a big impact on other Chinese. For example, Wong Jingwei thought if the army just ran away, China had to make peace with Japs at any cost. Ran away is not the same as being defeated.