Since they say the shoyu soup is the famous one, I ordered the char siu shoyu soba (less salty). And indeed this was much better than the shio. The shoyu had a smooth deep flavor that harmonized well with the truffle oil. After stealing some char siu from hubby's bowl, I finished his soup straight from the bowl. The truffle oil fragrance was strong in my nostrils as I chugged down the savory soup. Yummy!