I think I found it at night time (got to sleep to pass time) and then there will be a dude standing next to three statues in one of the road. Not really hidden.
The yukata you have to get the bug net, to get the bug net find the bug uncle to get the keys from the river going to the house in the deep forest, hes in the path going to the lake, to get the parts you trade them with the ghost, from what the Walkthrough says, once you finish the the loincloth mission you go to the village and in one of the houses, there would be a guy with weird glasses who repairs it. Anyways, i still havent found the guy, can you specify more where he is? because the only guy next to three statues is the bug uncle.
Is at night on the first map with the pier where you first arrived, there is a dude on the top part of the map, also in the same map you can also find the bottom part of the swimsuit at the end of the pier
The yukata is on the chest next to Misaki but for that you need the net and also interact with the shiny in the water where the ladder is, after you inteact with that go to the map where you used the ladder there is another interaction where you need to use the net, and after that you can go open the chest to get the yukata
You got to find him three times. First time is on the path to the secret beach, then at the beach north of the ninja chick, lastly he's in a hole you pas up going to the village in the beginning of the game
