Try farming some R-Gacha tickets for a couple of days (via the chance rolls mision), and then go for Kurito plus some other items.
Many people here got the limmed SSR just with silver buttons, and I got mine with a golden button (can't remember the exact materials since I wasn't expecting that to work, lol, but I think it was something like R-tickets + Peronamin + Card reveal and another random item).

Event just using 1 R ticket may work, but from what has been said here, odds are very low, so I wouldn't recommend that. Try R tickets plus something else. :3