Miseinen wa Kyuuketsu Kinshi desu!

The manga centers on Yoshikage Muroii, a young vampire, raised by his father to be kind to others and to never suck blood from minors, and has lived by those principles his entire life. When he enters high school, he starts living by himself for the first time. Through a messaging service exclusive to vampires, Yoshikage gets to know someone named "Spider-san," and arranges a meeting with the person. While "Spider-san" presented as a male online, Yoshikage instead meets a girl of the same age as him.

(Source: Anime News Network)