why advanced system. Having a full living soul in your head will affect your psyche and cause your main personality to be not always decisive. like multiple personality .

why harem? it destroys men?

will the updates be regular

what about sharingan. he asked for knowledge of chakra and eternal youth. If you have something then use it. Then there is using Madara's fighting experience to train fire bending which is not ideal tran the taijutsu while increasing chi and chakra pool along with chakra control after perfecting them fire bending will be much easier since Madara's primary chakra nature was also fire. That's how I would have done it, that's what's best for the long term. Know that Madra has been fighting in wars since young he not only just have knowledge from konoha Uchihas are one of the oldest clans in Naruto world.

Sorry, I lost my interest when I read about summoning stuff..

Just don't use 'cuz', and try to use good enough grammar and punctuations.

I think it's good. But I got bored easily

liked the start but I don't like the summoning function, sorry..!