The "gakuran" is a military-based uniform for Japanese boys in middle and high school. It is almost as famous in Japanese animation (called "anime") as the sailor uniform for girls, and consists of navy blue or black slacks and a high-collared jacket with gold buttons down the centre-front. The gakuran is usually without other adornment, making it relatively easy to draw.
Sketch a boy's figure in light pencil lines before drawing any clothes. Make him relatively stationary, standing with his arms at his sides, for your first attempt. This will decrease the need to draw wrinkles in his clothing.
Draw the gakuran slacks lightly over the figure without erasing anything. Gakuran slacks are like dress trousers, straight with a crease down the front. The hem stops at the ankle.
Note where your figure's pose will create wrinkles in the fabric. For example, if his knee is bent, creases will start from behind the knee. Put on slacks and pose in front of a mirror if you want to see for sure.
Draw the gakuran jacket so that it falls below the waist, about halfway down the pelvis. Draw thick, straight lines to show the material is stiff. Keep the cuffs just below the wrist and the collar high and straight with a white border at the edge. Draw five round, gold buttons, evenly spaced, horizontally down the chest. Draw two pockets, one at each hip.
Design a logo for the imaginary school your anime boy goes to if you want to try illustrating details. Put this logo on his gold buttons, and a pin on his gakuran collar (this pin might be special, also showing his class and year).
Draw sneakers or loafers on your figure's feet if you want to be realistic, though other footwear can be attempted for fun. Try drawing boots only after you gain some experience. They change the lay of the fabric and give you many wrinkles and shadows to deal with.
Once you are pleased with how your gakuran looks, draw over the final pencil lines in ink. Wait for the ink to dry, then erase visible pencil lines.
Professional artists often draw figures in light blue pencil (rather than using light pencil lines), as blue pencil doesn't show up when photocopied. In summer, the gakuran jacket is usually discarded for a white, short-sleeved button shirt. The slacks remain. The gakuran is the most famous Japanese uniform for boys, but some schools have sweaters and slacks or suits and ties. Go to the home pages of Japanese high schools to research. Even if you can't read Japanese, many sites will have pictures. As this is anime, you're always free to get creative with uniform details, changing fabric colours or adding accessories and designs.
Don't erase the pencil lines until you know where all your final lines will go. Erasing too often will leave a sheen on the paper that looks sloppy and is difficult to draw over.