[ST18-005] - Luffy-Tarou (Starter Deck 18: PURPLE Monkey.D.Luffy)

When I had 7 DON!! cards on my field and my opponent had 6 DON!! cards on theirs, I played "ST18-005 Luffy-Tarou" and used its "[On Play] DON!! −1: Play up to 1 purple {Straw Hat Crew} type Character card with a cost of 5 or less from your hand." effect to play this card after returning 1 of my DON!! cards to my DON!! deck. In this case, can I use this card's [On Play] effect to draw 1 card?

Yes, you can.