Possible Clues:

• Fortress has alcoholic drink - something treasured
• Souvenir or memento
• Gift, reminder
• So it turns up where there's wars around
• Memento, souvenir
• It serves to keep a person in mind
• Memento taken from part of castle before Eastern drink
• Something made fortified Japanese wine a thing to remember
• In Tokyo, barmen do it as a reminder
• What helps one remember to stock rice wine