This is a Sashigane-Statue Park hybrid. The rules might look complicated, but they're just the two rulesets smushed together. Familiarity with both genres will help.
Statue Park (adapted from the question Statue Park: Knight's Lines)
- Shade some cells to form the given set of pieces (in this case, a single tetromino set)
- Pieces can only touch at corners (so they can't be orthogonally adjacent)
- All unshaded cells must be orthogonally connected
- Cells with small black circles are shaded, and cells with small white circles are unshaded
Sashigane (adapted from Nikoli)
- Divide the unshaded cells into L-shaped blocks, one block wide. All unshaded cells must be part of an L-shaped block
- Cells with large circles form the knee, or bend, in a block
- The number in a large circle denotes the number of cells in its block. Large circles with a question mark (?) may be part of a block with any number of cells
- Cells with arrows form one end of their block, and the arrow points towards the knee
- The number of markings (arrows and large circles) in a block may be 0, 1, 2, or 3. In other words, a block may have or not have an arrow at either end, and may have or not have a large circle at its knee.
The small white circles for Statue Park ARE NOT large circles for Sashigane. Statue Park's small white circles may be anywhere in an L-shaped block - at an end, at the knee, or neither.
Now that you've survived the rules, the actual puzzle. I've included all tetrominoes as a reference.
Nothing below this line is strictly necessary to solve the puzzle. It's just some useful information/tools, as well as clarifications about what kinds of answers I will accept.
Here is the puzzle in a Penpa editor
The first answer with a fully-explained logical solution path will get the checkmark. A full solution will have all cells confirmed either shaded or unshaded (for Statue Park) and have borders drawn in for all L-shaped blocks (for Sashigane) I welcome multiple answers, if later ones can show a better-explained, more elegant, or significantly different path. Please do not answer without an explanation/solve path.
Here is a tabular transcription good for copying into a spreadsheet. Ignore the header row; the first row with a circle is the first row of the puzzle. The Sashigane circles are depicted only by their contents. So the "5" is a 5 in a large circle and the "?" is a ? in a large circle. All circles shown are Statue Park clues.
Crash course in Penpa: Things that might be helpful to solve the puzzle
- To change the background color of a cell, click on "Surface" under "Mode", select the color you want (e.g. "Light grey"), and click on a cell. I recommend choosing one color for "confirmed shaded" and one color for "confirmed unshaded". Don't use too dark a color for unshaded cells or else the borders won't stand out.
- To draw a border between cells, click on "Edge" under "Mode", select the type of border you want (e.g. "Fat"), and click-and-drag along a border. The "Fat" after "Dotted" is a dotted fat border. I recommend not using thin or dotted borders; they do not stand out as well.
- To draw a connecting line between two cells, click on "Line" under "Mode", select the type of line you want (e.g. "Thin"), and click-and-drag between the centers of two cells. I recommend doing this to notate cells that a border cannot divide.
Finally, I would like to thank Sciborg. This puzzle type was dreamed up while we were DMing in Discord; they couldn't decide if they loved Sashigane or Statue Park more. The obvious move was to combine the two genres.