I think I need to give a feedback as well, so here it is:
The mythic items have been added on test server a few days ago. The player feedback in discord and in some discussions was that a) mythic items cost WAY too much kobans, b) they block market places for epic/legendary items c) because of feedback a and b, the affection/girl's xp problem gets way worse for most of the players because nearly noone wants to spend kobans to level the girls and the amount of kobans increases drastically to get the same amount of xp/affection as before d) change the way mythic items get implemented (the ideas @jelom posted in his post).
Today the mythic items got into the game with a 33% reduction in koban cost, but nothing else. This makes me kinda disappointed, it was foreseeable that players react badly on this change because the problem kinkoid adresses is not solved, but intensified.
Just another thought: Why should anybody spend that much kobans to level his/her girls? You hardly get anything out of it (unless the affection scenes when you increase the star level of the girl). Yes, in LC you get an insta win on 4th day, but most of the players who want the girl in LC have her already on day 4. I rather spend my kobans to get more girls during events or in pachinko, but I won't spend kobans for mythic items (if they are only books and gifts).
@kinkoid: prease overthink these patch notes again and do something that really solves the affection/girl's xp problem, you may can use some of the ideas in @jelom's list.
I add another idea: increase the restock koban prize, but make the mythic items only cost Ymen. Then, people are more likely to restock (and spend a little more kobans than they do now) but they feel rewarded as they finally can level their girls.