Aomori is one of the BEST places to try fresh and delicious sashimi in Japan (especially TUNA!)
At the Furukawa Fish Market (a short walk from JR Aomori Station) you can make your own tasty seafood bowl using their ‘Nokkedon’ system: buy a book of tickets and walk around the market exchanging them for your favourite pieces of fresh-as-fresh sashimi! Itadakimaaaasu!!
More info here:
AloJapan.com