When we travel to Europe with Finnair, we are very fond of shopping at the Helsinki airport, stopping by the Moomin shop and the Marimekko shop.
Moomin shop can be found in the Schengen area and also in the Japan-bound terminal. The shop is larger and has more items in the Schengen area. If you are traveling from Japan to Europe, I recommend the outbound trip, but duty free procedures are easier at the stores in the Japan-bound terminal on the return trip.