Well. Like others said, try the cross over for 4 tickets and do the reissue for a 5* Hypericum.
Tuesday we will got the new event. I'm not sure what kind of event it will be but pray for one where we can get the girl before the end.
You also have the valentine log in bonus with a lot of FG to use.

If you are lucky, you can get 6 5* in less than a week.

And since you just started, you also can create multiple account (and use your invite link findable in your nutaku profile) and use your free FG on the gacha until you get good girls (maybe a 6*?).

And if you need a strong ally on the harder stages, I still have a free slot