I can't figure out if the girl is making up obvious lies (mutant shark? and an exorcist considers it in the scope of her job?!? lol) and brought him to the beach for a date, lowkey hoping he will figure it out.
Or if this manga takes place in the kind of world where the scenario she brought up actually is legit, and she brought him hoping to use his ghosts as support (or to make it double as a date as she has to visit the beach anyway). The latter is not actually that absurd of an idea, considering the rest of the manga and its characters.