I just finished watching Clannad episode 23 and looks it coming to its end. Left one episode and as I believe that last episode won’t cover the whatever remaining unexplained matters throughout the anime, I went to search for some info and found out a trailer at youTube titled Clannad- After Story. Its only a promo, but I need to verify whether its an OVA or a second season. Confirmed the clip was the sequel to Clannad.