The leaves on the most affordable branch of my plant are turning brown, though those on other branches are green and healthy. What is incorrect?
Yeo Khoon Kee
Your bonsai appears like a Juniperus, which is a sun-loving types that requires direct sunshine for a minimum of 6 hours a day. A shaded area such as that displayed in the image is not ideal, as the absence of light will eliminate the leaves.
Also, make sure that the soil is neither too compressed nor too clay-like, as roots that are too wet or dry will pass away and be not able to use up water. Wet feet can likewise cause illness.
In a house setting, which is not as warm as the outdoors, the root zone might not dry out rapidly enough, so you might require more oxygenated and well-draining soil.