Now this one's a bit weird. The key character here is "意", which I interpret it as "thought". But just in case, I looked it up a bit more. Another way of pronouncing this is "Kokoro". However, Kokoro's name is straight hiragana, so that's unlikely – not to mention the usual kanji for "Kokoro" is not this character.
It is used in Eirin's 八意 though. Yes, what I'm saying is Eirin's surname is literally "Ya + Kokoro". But due to the pronunciation convention, "Yakokoro" becomes "Yagokoro".
