It seems like you're incapable of reading yourself . Or you'd have seen where I said your initial assumption didn't make sense. Then went on to say that he'd likely be making 2 trips a weekend . Which is 12 trips total (3months * 4 weekends) and no where near his whole paycheck unless MC is broke af. You should keep your speaking down to others to a minimum, especially when you're wrong
Do you understand that 100 one-way tickets is 50 round trips? I mentioned that in contrast to annual (yearly) salary because that's the number of weekends in a year rounded down. It was provided in general terms first because I was replying to someone who was complaining about it showing up in many different stories.
The specifics don't change much here, other than both halves of the couple being adults*, and not knowing where they live other than 2 hours from Tokyo by shinkansen, so something like Nagoya/Sendai/Niigata is about the right distance. Rounding down 3 months to 12 weekends is fine (it's 13 but that changes nothing), which means 12 return trips, or 24 one-way tickets (you can buy return tickets for shinkansen trips but they generally seem to just be listed as the same price as two one-ways).
The fare structure for shinkansen tickets is a bit silly because it includes a base ticket price for taking a train ride at all, then lists surcharges for the shinkansen itself, but round down a current Tokyo-Nagoya/Sendai/Niigata shinkansen one-way ticket and it costs 10k yen. 24 of those is 240k yen.
So how much money does he have? He's a 20yo college student who lives outside of Tokyo and tutors Miu. He's not a full-timer earning something comparable to the national median earning around 1.4M yen in 3 months. Minimum wage in japan varies by industry and prefecture but they're mostly a bit below 1k yen per hour, and nationwide average for part-time work is a painfully low 1.1k yen per hour. So I'll be generous and give him 1.2k/hour, which means those 3 months of weekend trip tickets will cost him 200 hours of pre-tax income - say, 16 hours per week.
But hey, maybe he's working 25 hours a week, maybe even more, maybe only 60% of his paycheck is going towards train tickets! Realistically it's probably manageable if she is making good money and paying most of the way, but it's still a lot of money to be flushing and that's why it's not unrealistic that the characters never mentioned the idea of just constantly visiting her that way.
*not the case for many of the stories the original poster may have been complaining about, highschoolers are going to have an even rougher time affording regular shinkansen rides