Temporal variation of high-temperature coronal structures observed by Hinode/XRT. The red-colored X-ray images are displayed over the radial magnetic field (B_z) images that are closest in time to the X-ray images in panels (a) and (b). The radial magnetic field image is obtained from the SDO/HMI SHARP series in panel (a), whereas the radial field image in panel (b) is obtained by Hinode/SOT-SP, because of the data gap in the SDO observation. The white arrow in panel (a) indicates a small bright loop in the north of the intruding negative peninsula. The background Hinode/XRT images in panels (c) and (d) are the same, whereas the magnetic polarity inversion lines of the radial magnetic field (B_z obtained from SDO/HMI SHARP) are overlaid only in panel (c), depicted as green lines. The sky-blue arrows in panels (c) and (d) indicate a dark tube-like structure along the magnetic polarity inversion line between P1 and N1.