I'm happy to hear you enjoyed all 3 pieces!
1) It's a cool scale for sure because when people think of Phrygian they think of dark but if you take away a few notes it kind of sounds bright go figure >_>. If you do try it out and want to be accurate Pelog Selisir is an Indonesian scale that has some microtonal tunings (so it's not really a Phrygian subset, it's more or a microtonal Phrygian subset), I don't have a link to the tunings off hand but I bet you can find the tunings online pretty quickly with a Google search if you want to be a bit more authentic to the source.
2) Yeah maybe it's the strums, the notes don't play all the the same time but I think that's intentional (as the koto is a zither instrument so I try to play it in strums, I try to keep the physical limitations of the instrument in mind when composing). Really the goal of mine was to get the instruments sound natural like a human is playing them rather than exact, as if a human is playing a real koto the playing will not be perfect too.
As for the trap beat, I like hip hop and it just seemed to fit the Yakuza theme I was going for so I went with it lol. Probably the most out of place instrument in all the pieces, and true not the most ambient but it fit the story I was writing and I'm a sucker for Roland Drum machines lol.
Yeah and as mentioned at the top of all the text part 1 was my originally my only submission (and the most ambient one that fits the theme) but I decided to just continue the story as I was curious to where this secret lake led me so you can think of parts 2 and 3 kind of like bonus content that I may have taken a bit more liberty with than strictly following the theme. I just wanted to know what happened next!