Tochigi Prefecture
noun
The prefecture with lots of horse chestnut trees is Tochigi prefecture.
とちぎけん
This word consists of the kun'yomi readings for 栃 and 木 and the on'yomi for 県, like most with prefectures. As long as you remember that き is changed to ぎ here, you should be able to remember this reading easily!
栃木県の出身なんですか？
Are you from Tochigi Prefecture?