diagonal, slanting, oblique
斜 centers on a line or direction that is not straight: diagonal, slanting, or oblique. All given meanings describe this same tilted orientation.
斜 combines 余 (excess, surplus) and 斗 (a measuring ladle). The original idea may relate to pouring or measuring with a tilted ladle, producing a slanted or diagonal orientation.
The left side 余 suggests something extra or overflowing, and the right side 斗 is a ladle. Imagine pouring from a ladle at an angle so the liquid flows diagonally: that slant is 斜.
For シャ, picture a shah (a king) tilting his crown at a jaunty diagonal angle: shah -> シャ, and the slant matches the kanji's meaning.
slanting; tilted; sloping; diagonal; oblique
inclination; slant; slope; bevel; list; dip; tilt; lean
slope; slanting surface; bevel
diagonal
steep slope
setting sun
oblique line; forward slash
slope; sloping ground; sloping lot
strabismus; squint
hypotenuse; oblique line
oblique type; slanted type
inclined shaft
in a bad temper; cranky; crabby
Leaning Tower of Pisa
triclinic crystal system
obliqueness; deviation; slantedness
progressive increase in rent
gradient
priority production
priority production system