Prior to the New Guinea/Solomons campaign, the IJA had little to do with IJN operations with the exception of the invasion of the Philippines.
The Army was focused and equipped to operate on the mainland (China, Burma, India, etc.) while it was up to the Navy to handle their own operations elsewhere.
With the deteriorating situation in the Solomon's, the Navy did request the Army's help and after many months of meetings and deliberation, the Army finally relented and transferred men and assets to the area.
The IJA had air bases in areas such as Wewok (New Guinea) and a joint base with the IJN at Rabaul.
The Army's air elements remained under control of the Army, though and "assisted" the Navy on their own terms.
As far as IJN camouflage, the units that operated from land bases adopted appropiate markings for the area: typically the dark green upper with the light undersides, though there were a few exceptions.
It was the Army that had the best camouflage, in some cases, better than the Italians!