I Want to Let Saejima-sensei go is a Manga/Manhwa/Manhua in english language, manga series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Thanks to an accident, Tanaka is able to see ghosts. One day, he visited the infirmary because he felt unwell, but the school nurse, Saejima-sensei tells him the shocking truth? A new spin in the horror comedy genre!