Mujirushi Ryohin 無印良品 carries a wide variety of food products in their bigger stores. Based on a recommendation from a friend I checked out a few things.
uni ウニ(sea urchin) pasta mix - thumbs up! Delicious.
ika sumi イカ墨 (squid ink) pasta mix - good too. But not as completely delicious as the sea urchin pasta mix.
Japanese matcha 抹茶(powdered green tea) latte powder - disappointing. It's quite sweet but not enough of a matcha flavor.
I also bought a chai mix but based on the matcha latte, I have very low expectations - most chais are not spicy enough for my taste to begin with (Starbucks, I'm looking at that vapid liquid you call chai).