So, still no clue for the tree. However, I finished the game.
It takes 4 hours if you focus on clearing the game, with a reasonable number of upgrades.
Which means I can give a review, and a save file. Unfortunately, there does not seem to be a gallery. However, you can easily teleport to every level and check the animations.
Overall, a solid 9/10 for its price and being the circle's first game.
The positives:
* Great graphics and monster designs
* Great concepts for H-scenes. A large number too (20+).
* Gameplay is great. No collision issues, no weird gravity stuff
* Some legitimately good gameplay sequences
* Difficulty is balanced
* Great boss fights
The negatives:
* Lacks quality-of-life stuff like a gallery, a map, or button mapping (especially a map)
* An english translation would be very appreciated, as the story is told through notes and examination of the scenery
* A few hitbox "issues": monsters at very close range are not touched by your shots, you can get looped into H-scenes if you are not careful (especially with the bugs)
* No boss H-scene and only 3 generic game over screens
* A lot of rooms have several enemies of the same type. Double-team animations would have been a nice bonus. Perhaps in an update (fingers crossed)
N.B.:
Rename the save file's extension to ".sav", then copy it in your C:\Users\...\Appdata\Local\Setaria folder