Naruto: Immortal Body from the Start

I'm confused because the protagonist is immortal and I'm afraid of the side effects of opening all 8 doors. The immortal body is just like Hidan, I can't even die if I keep opening 8 doors.

Start by poisoning and working in prison*

Do you understand Naruto's heart? He also said they were hypocritical

You are immortal, and you have a system. Do you think seizing the body is useful for the protagonist? , You are sure that the protagonist is a time traveler, and you are sure that the protagonist understands the word system