>>3777417The only thing I felt fell under "very easy to miss" would be Kaguya's recruitment condition, as the trigger for taking her route over the default that recruits Kenshin Koishi is both nonsensical and only open in a very small window
You have to go to the Noble District in Daito and talk to one random-ass NPC who alternates what they say on a 15 min timer where one thing they say keeps you on the default route and the other puts you on the Kaguya route
If she didn't show up in the game's opening, I would have never known she even existed or searched the GameFAQs message boards looking for the answer on how to get her.