Whether curved or straight, the whole trunk leans at a definite angle. The stronger roots grow out on the side, away from the angle of the trunk lean, to support the weight.
Conifers work particularly well.
This style is quite a simple one that can be achieved by many methods. At an early age, the bonsai can be trained to an angle by means of wiring the trunk until it is in position. Alternatively, the tree can be forced to grow in a slanted style by putting the actual pot on a slant, causing the tree to grow abnormally. With formal upright, informal upright and slanted styles, the number three is significant. The lowest branches are grouped in threes, and this grouping begins one-third of the way up the trunk.