Dongdong: In light of the recent feedback about the protagonist's combat strength, I'm officially correcting an earlier detail-his Sage Mode is imperfect and can normally reach only 50%.
Actually, when Tagorihime taught him to enter Sage Mode earlier, it was also at 50%. I may not have emphasized it enough, which led to some misunderstandings.
The main revision is in the fight against the Mizukage: when the snake tail appears, this point is specifically emphasized. I left it out before to avoid too much explanation during the fight. (Earlier, in Ryūchi Cave, I did emphasize that there was no snake tail at 50%.)
Under normal circumstances, Akaseki's Sage Mode reaches only 50%, and he needs to open three gates to stabilize his mental state. (It's not that he didn't use three gates; opening them is already a prerequisite for his Sage Mode, much as Jiraiya needs the toads' cooperation.) He has no snake tail at that level. In the final move that subdued the Mizukage, Akaseki exceeded his normal limits and reached 60%.
The protagonist's Sage Mode still has room to improve. (It essentially progresses in sync with the Yin Style Eight Gates.) As his Sage Mode deepens, both its form and its level of combat power will improve. He hasn't already reached its ceiling.
[This passage was added afterward and isn't included in the charge.]
"Are they insane? They've chased me all the way here, and they still won't stop?"
"Is that son-in-law deliberately screwing me over? Manda should have received the message by now!"
"If this keeps up, my chakra can hold out, but Tanuki Treasure probably can't..."
"The Land of Whirlpools... sealing..."
"Fine! Keep chasing. Don't regret it!" Seeing that he had already reached the coastal waters of the Land of Fire, Akaseki steeled himself...
There