Why Japan kept favouring heavy cruisers over more light cruisers

Why did Japan favour heavy cruisers instead of building more numerous light cruisers?

The navy tried to combine scouting and combat in one ship, but inadequate industrial preparation prevented treaty withdrawal from producing a more coherent force mix.

Japan favoured heavy cruisers over larger numbers of light cruisers, but both categories struggled with the tension between scouting and ordinary cruiser combat. Once the Fleet Faction took Japan out of the treaties, legal limits no longer explained the continuing compromises. The binding problem was that shipbuilding and supporting industry had not been expanded to match the new ambition. A more coherent force would separate reconnaissance aviation from cruiser fighting instead of asking an expensive heavy cruiser to perform both. Strategy and industrial structure mattered more to the imbalance than any single fuel calculation.