Japan's plan had no comfortable answer to an active defense

What was the Japanese plan for dealing with an active defense over Oahu?

There was no strong alternative plan because Japanese modeling and war games assumed that the raid would achieve surprise.

The Japanese raid was designed and rehearsed as a surprise attack against a concentrated fleet. Japanese modeling offered no good plan for meeting an active Hawaiian defense. Fighters in the air, ships moving, and targets no longer sitting at expected berths would disrupt the attack's assumptions as well as add attrition. An American victory remained uncertain, but even partial warning could have reduced Japanese effectiveness out of proportion to the defensive effort.