The characteristic features of a 3D digital printed round neck short sleeve shirt with a black base and a cartoon Japanese man pattern are as follows:

1. Unique and Eye-catching Design: The combination of a black base color and a cartoon Japanese man pattern creates a visually appealing and attention-grabbing design. This distinct and trendy design stands out and instantly attracts the attention of young people.

2. Personalized Style: 3D digital printing allows for a high level of customization, making each shirt unique. Young people often seek individuality and self-expression in their fashion choices, and this personalized style of shirt caters to their desire for uniqueness.

3. Japanese Pop Culture Influence: The cartoon Japanese man pattern reflects the influence of Japanese pop culture, which has gained significant popularity among young people worldwide. This design choice resonates well with young individuals who appreciate the aesthetics and trends associated with Japanese culture.

4. Comfort and Versatility: The round neck and short sleeves make this shirt comfortable to wear, suitable for various casual occasions. It can be paired with jeans, shorts, or skirts, allowing for versatile styling options that suit the dynamic and ever-changing fashion preferences of young people.

5. Reflects Youthful Energy: The combination of a lively cartoon pattern on a black background exudes youthful energy and vibrancy. This shirt conveys a sense of playfulness and enthusiasm, making it a suitable choice for young individuals who want to express their youthful spirit through their clothing.

In conclusion, the 3D digital printed round neck short sleeve shirt with a black base and a cartoon Japanese man pattern is suitable for young people due to its unique design, personalized style, Japanese pop culture influence, comfort, versatility, and reflection of youthful energy.