The 'variables.json' file in the Misc. folder has the list of idol names the game can generate. You can add, remove or edit the pool by modding that file. The pools are divided into three categories, though: male names, female names and surnames. You might have to work your way around those limitations to get the results you wish to have.
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You're welcome!
In order to change all the idols' gender to male, you'd need to fiddle a bit with the game's code, though I'm not even sure that would be possible at the moment. For now, I'm afraid the only way to get the idols to have male names is to replace all female names from the list with male ones. Devs might have answers more detailed and accurate than mine, though.