Taboo (табу) is custom, called also unwritten rule, characterised in that, that the supporters believe, that the custom is extremely important, but cannot provide any reasonable explanation for this importance nor reasons for this belief.
http://www.theguardian.com/world/2013/nov/07/japanese-politician-letter-fukushima-emperor Taro Yamamoto faces criticism after handing note to Emperor Akihito at garden party in breach of strict protocol. Thursday 7 November 2013 09.24 GMT. Yamamoto denied any intention to use the emperor for political purposes – a possible infringement of the postwar constitution, which relegates the emperor to a non-political, ceremonial role. "My behaviour was indiscreet for a place like the garden party," Yamamoto said at a news conference on Tuesday. "I just wanted the emperor to know the reality. I was frustrated by not being able to achieve any of my campaign promises yet."