If a particular candidate is present in only four Cells in four Rows and if these Cells belong to the same Columns forming a four-by-four rectangular pattern, except for one Row where one of the Cells, called the "sashimi" Cell, in the four-by-four rectangular pattern is solved (either by an initial value, or by an induced value) and where the candidate is also present in Cell(s) of that Row that belong to the same Square as the "sashimi" Cell (these extra-cells are called the "fin"), then the candidate can not be the solution for any Cell in the Column of the Square containing the "fin".

Indeed, either the candidate is the solution for a Cell in the "fin" which eliminates it from all other Cells in the same Square, or it is the solution for one of the Cells in the four-by-four rectangular pattern in the same Column as the "sashimi" Cell.

The reasoning is also applicable when you replace "Row" by "Column" and "Column" by "Row".

The candidate must not be present in all Cells of the pattern, as long as the Cells where it is not present are "solved" Cells (i.e. either contain an initial value, or an induced value).

In the example above, the four-by-four rectangular pattern is comprised of Rows "B", "C", "D" and "E", and of Columns "1", "3", "4" and "7".
The "sashimi" cell is E4. The "fin" comprises E5.
If candidate 5 is the solution in B1, then it must be the solution either in C3 or in C7, which implies that it must then be the solution in D4 or in E5, which eliminates it from all Cells in Square "5" (in particular F4).
If candidate 5 is the solution in B4, then it eliminates all candidates 5 in Column "4" (in particular F4).
If candidate 5 is the solution in B7, then it must be the solution in C3, which implies that it must then be the solution in D4 or in E5, which eliminates it from all Cells in Square "5" (in particular F4).
Whichever the solution for candidate 5 in Row "B", it can never be the solution in F4.

You can practice this strategy by installing the SudokuCoach application on your Android™ device.