Gold Star 3 and Gold Star 4...

I want to get Dyna-Dragon and Kaiser Gridknight during the collab period, but... one is Gold Star 3 and the other is Gold Star 4... The drop rates are low... Plus, I'm probably also aiming for the Ultraman from the regular event (said to be The Next from the movie ULTRAMAN, perhaps the form before Ultraman Nexus...), so it's tough... Especially for free-to-play players... I was so hyped when I luckily got Zero Cosmo-Rise or Ultraman Tiga (activates type change during special move) in previous events.