a flashback is when you watch something you've seen before like when naruto flashbacks and remembers what others have said to him before. this is hashirama telling his events when meeting madara and the events that shaped him towards creating the village system. we know they fought but we never knew they got along and they didn't meet on the battlefield like most readers would guess having not known anything about their past aside from their clans being hired to fight each other. we also got confirmation that their clans were rivals not just solely for the purpose of being hired to take each other on while fighting for someone elses motives. this was part of the actual story line like it or not it is not a flashback because we have never seen these particular events before and aside from the sasugay and naruho kiss, which was a joke, i dont believe there has been any actual gay references in the entire manga... if you dont want to read the manga then dont but a ridiculous rant about what the manga has been about since day 1 and then making the strongest characters in the manga seem gay because thatsthe way your mind works is just arrogant on your part. Don't read it, wait for about another year or max 2 and it will be done then read it through and through and i bet you won't complain because the story will seem to advance when you can read them back to back