Wow, it’s looking more and more like a battle royale among this generation’s superstars in the spring drama season in Japan. There’s Oguri Shun with BORDER, a detective drama, on Asahi.   (Source)   Then there’s Arashi’s beloved Ohmiya with dramas of their own: Nino with the baseball-themed KOWAKUTEMO KATEMASU on NTV and Riida with SHINIGAMI-KUN…