The Jahi is an enemy in Final Fantasy X-2.
For the point of the game it appears in, it is not particularly threatening. Excalibur is all that is needed to take it down, but if that is not an option, using strong physical classes or powerful spells such as the Level 3 elemental spells (except for Lightning, as it absorbs it). It is not very difficult at all.
Jahi is the Avestan language name of Zoroastrianism's demoness of lasciviousness.