expression, ichidan verb
ensconce oneself; settle down comfortably; plant oneself
Idiomatic expression literally meaning 'to set down one's portable shrine', used humorously or emphatically when someone plops down and refuses to move, often in a chair or seat.
彼はソファにみこしを据えて、動こうとしなかった。
He ensconced himself on the sofa and wouldn't budge.
会議室の一番いい席にみこしを据えて、ずっと居座っていた。
He planted himself in the best seat in the meeting room and stayed there the whole time.