Nobunaga actually did build a castle overnight, across the river from Imagawa castle without being seen. It’s believed that he only finished the skeleton, not the entire thing, but I think the show looked pretty accurate in that respect.
However, the battle played out differently. The residents of Inabayama Castle didn’t attack, and were actually the defenders. The whole thing with Nobunaga going into a trap never happened, although some of Dousan’s retainers did defect to Nobunaga’s side. Imagawa castle was renamed Gifu castle after the battle.
It’s also a battle that was important in the monkey earning an important role in Nobunaga’s eyes. This is where he gained his name of Hideyoshi, which is why he was so surprised when Nobuna picked someone else to be in charge.
I’m sure I wasn’t the only one who was disappointed when it turned out the loli ninja wasn’t really dead. Not to say I was surprised. That was a pretty cheap move to gain sympathy though. The whole castle is on fire. Oh, wait, but everyone’s fine! Yeah, sure.
And this was quite the understatement. Also, is her armor made of spandex or something? I don’t get how her breasts can jiggle so much. Maybe it’s some more of that ninja “chainmail.” I guess armor doesn’t really matter anyway, since Saru is going around fighting everyone in his school uniform.