Solution: Gojira

Written by Kevin Wald

As hinted at by "Coordinate the data, both horizontal and vertical," the solution involves taking the numbers in the horizontal rows as x-coordinates, matching them up with the numbers in the vertical columns taken as y-coordinates, and plotting the results on the supplied coordinate grid (with the origin in the lower left, indicated by the circle). Specifically, for each row and corresponding column, we trace a path from point to point, lifting the pen up at every color change. These four sets of paths:

(2, 4) (2, 0) (1, 1); (0, 3) (4, 3); (0, 1) (1, 2); (3, 2) (4, 1)
(1, 4) (1, 2); (4, 4) (4, 2) (2, 0)
(0, 4) (1, 3); (2, 4) (3, 3) (1, 0); (2.5, 4) (3.5, 3); (3, 4) (4, 3)
(0, 4) (1, 3); (0, 1) (1, 0) (4, 3)

yield four line drawings (one for each row/column pair):

Gojira solution diagram

which are the Japanese katakana for the syllables HO, RI, ZO, and N respectively. (There are several hints in the introductory material that something Japanese-related is going on: The reference to Godzilla, a creature from Japanese films, by the original Japanese form of his name; the mention of the "rising sun"; and the superficial resemblance of the puzzle to a "Paint by Numbers" puzzle, a type which originated in Japan.)

Thus, the solution, "where Gojira was last sighted", is HORIZON.