Kirk here. This type of archery is called “yabusame” (流鏑馬). I think that, in combination, the first and third characters mean “running horse.” The second character refers to something that is put on the tip of an arrow to make a cool sound when the arrow flies (or perhaps when it hits it’s target). At any rate, the archery event will be conducted between 2 and 3:30 on November 3rd, Friday, which is “Culture Day” (文化の日). The venue is Ninomaru Hiroba (the castle).
https://kumamoto-guide.jp/oshiromatsuri/events/detail/72
By the way, here ’s a video of a similar event held at Aso Shrine earlier this year:
