These horns grow fully sideways. They do not have angles fowards or backwards, only variating if they grow downwards or upwards.
Sidways style horns are not the best for battling, and can excessively drag a Hanasei underwater. Their main bonus is a better self-defense, but the advantages often don't compensate for the difficulty in active swimiming and fighting. This caused them to be way more rarer for a long while.