Izuminokami makes the most disgusted look at the mere thought of his hair being bland and lank. His hair was one of his best features!... Well actually if one were to ask him he'd pretty much list all of his physical features as his best features, but that didn't change the fact that he didn't like the idea of his hair being boring and lanky looking! So of course he takes Tonbokiri's words seriously and only takes a few drops of oil to begin working through his hair.

He even had such a seriously look on his face while he did it....

"Who would have guessed, keeping up one's physical appearance this way would be just as difficult as training our physical bodies..."