multiple digraphs in vim

Question

As you probably know, there is ability to enter some specific characters in vim using digraphs (In input mode Ctrl+K Rg produces ® for example).

Is there a way, to define hotkey, to enter the mode which allows me to input multiple digraphs? For example, to write "sayonara" instead of "Ctrl+K sa Ctrl+K yo Ctrl+K na Ctrl+K ra" to get "さよなら".