I've read from several articles that frequent masturbation can cause prostatic hyperemia and thus cause prostatitis. is that real?

Reading is good: Reading is good, and makes a young person well-rounded and wiser about affairs of the world. One's prostate gland does not know where one's penis is (for example, outside the girl vs. inside the girl), and one's prostate does not know how the penis is being stimulated (for example, with hands vs. inside the girl). So, the effects from vaginal sex or masturbation appear identical to one's prostate.