<p>Jiraiya's imperfect sage mode arguably gives him some physical advantages too. I personally don't think there is anything wrong with being an imperfect sage as long as you have ma and pa. Jiraiya was able to balance the energy enough to avoid becoming a statue , and from there a perfect sage mode has no real difference in power with an imperfect sage, it's just the physical features that are different. So with ma and pa, jiraiya can maintain sage mode for a longer time and doesn't have to worry about balancing any further nature energy himself , and he gets the added bonus of genjustu plus Sage Art Goemen.
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