I went sightseeing Phnom Penh and Siem Reap last summer vacation.
Phnom Penh is the capital of Cambodia, as you know Cambodia is a country that is developing intensely now. Everywhere in Phnom Penh was under construction, so after a few years, it must be a well-developed city in South Asia.
In Siem Reap, I looked around the famous heritage of Khmer cultures such as Angkor Wat and Angkor Thom. Especially, Angkor Wat was great that has many beautiful reliefs on the wall. From the reliefs, we can see how Khmer people lived in Cambodia at that time. Most of the reliefs depend on Khmer mythology or tradition, so travelers had better study Khmer culture to enjoy the heritages sufficiently.
Finally, I strongly recommend you visit Cambodia. The prices in Cambodia are lower than that of Japan, which makes university students who have no money travel easier, and also the heritages of Khmer are worth visiting Cambodia.