LogFAQs > #903174514

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So I shouldnt bother since Im already at level 3 with him?

No you can get to 4.

It won't let you progress past 4 until after Futaba's palace though (specifically after the whole arc is over and the time limit passes)

And his confidant rank goes up normally after that point too (as in, it doesn't take 5 billion years per rank- to clarify that's once you're at 4, not just because of the plot)