Nah what do you mean it has little story relevance. It evolved auto threat interception ability and can control the MC's body to cast spells he doesn't even know. With this kind of trend, it might become the ultimate magic system.
Number 3 turned out to be travel thousands of years into the future, of the Earth you already felt out of date in... Oh wait, I thought you were talking about his current business plan of traveling to Japan, for items that may as well have not existed in his previous lifetime. Nevermind.
No, if this is due to him bringing them isekai materials, then the Shrine Maiden would be someone who awakened to magic while exposed to the radiation (magic energy) of the materials that made space travel possible. I'm guessing it's that lightning ore, but it could be anything he imbued his Space/Time magic into as well.
Well, he's right about the "miko" being part of the family, in fact their ancestor or the founder of the Fuji/Fujinomiya family is Allen, but the wife hasn't yet been revealed, the candidate either Saionji or the maid, also one thing for sure "miko" only born as eldest daughter and second child onward didn't have any supranatural power
