Which one came first? PULSE or This? They have many similarities...Lol

The only similarity I can think of is that both of them have a black haired doctor. But the doctor characters themselves are completely different from each other.

Eh, There's a few others. Doctor/patient relationship, at least some level of age-gap, a pretend relationship that starts based on a contract and turns more serious...Sensei is definitely a very different creature from Mel, but there are some similarities.