Just FYI for those who do not already know, 2016 summer event is on, this time you have to access the place from the railway station in Onigashima :
http://onigiri.cyberstep.com/info/topic/update/9851
The event achievements are quite easy to get, mostly running up to a certain NPC or place on the event map. Here is a list of what I have so far:
1. Get close to Matsuri Watchtower.
2. Get to the Bar Counter.
3. Visit the Shrine.
4. A place to see the fireworks.
5. Visit Fairy Floss stall.
6. Visit Daruma family.
7. Go to Bug Catching contest grounds.
8. Go behind Chief Daruma.
9. I'm still missing this one.
10. Visit the Raincaller.
They mostly give Contest Use Bug Cages and Torn Pieces Gacha Tickets. Use the bugs from these and the contest grounds to trade with Kubire for Alternative Summer partner outfits/Summer Hats/Weapons/Magatama boxes/Amulet/Buttons/Aid/etc.
You can only get a maximum of 16 Oni's Snow Cones so that's only enough for 2 special partner outfits. The standard partner outfits are available for all.