The Tokyo City Philharmonic Orchestra will be performing all eleven Dragon Quest Symphonic Suites in sequence in concerts starting April 28, 2019, and ending March 27, 2020. I've been to a few of their Dragon Quest concerts before and they always put on a good, purely symphonic show. (No video projection, emcees, or other superfluous stuff, though the conductor - who has played his share of Dragon Quest games - tends to talk for quite a while at several parts in each show).
Here's a flyer with all the dates, and a page at Japanese ticket site Ticket Pia with current for-sale shows. For anyone thinking to visit Tokyo around the concert dates I would absolutely recommend their concerts - especially for DQ I-VI and IX.
Apart from these Tokyo City Phil concerts, almost every month there's a Dragon Quest concert happening somewhere in Japan. The best place to find these is the concert listings on Koichi Sugiyama's official website (figuring out the exact location will require sorting through some kanji).