Subaru plays an Astrodragon deck, focused around his Buddy's ability Galaxy F, which activates when he has a monster on the Center, a monster on the Left, and an item equipped. Skyseer Dragon, Cross Astrologia 's Galaxy F gives all his cards Penetrate and +1 Critical, allowing Subaru to do a very aggresive push, which he follows with his impact Tri-Star Decision to finish off the opponent should they survive his Attack Phase. Being the Ace of Study, Subaru often studies how his opponents' decks work beforehand and adjusts his own deck to prepare countermeasures against them, while also using multiple support cards so his own plays can continue uninterrupted
After being defeated by Seiji Kido'sOppress deck, Subaru's buddy, Astrologia, evolved into Skyseer Ardent Dragon, Cross Farnese Astrologia. With it, Subaru updated his deck so Galaxy F can also work with a monster in the Right, countering Oppress while also making his plays more flexible as Galaxy F can function differently depending on if he has a monster on the left or right.
"I'm guided by the celestial sphere! And the Guidance of a Dragon. Luminize! Triangulum Galaxy!"