Arranged to assist in a lab with 〜ことになっている

Grammar Explanation: Past decision still in effect with 〜ことになっている

Reika sees an unknown person in the old lab next to her class’s. She asks to woman if she’s an assistant.

せつな:: 「いえ　学生(がくせい)です理学部(りがくぶ)の」; “No, I'm a student, in the science department.”; 「こちらの研究室(けんきゅうしつ)のお手伝(てつだ)いをさせて頂(いただ)くことになって」; “It's arranged for me to help out in this lab.”; Literal: “It has become the thing that I will be allowed to help with this lab.”

Key Points

1ことになって presents an arrangement

〜ことになる says that a decision or arrangement has come about.
Here Setsuna explains her role as something already arranged, not as a sudden personal whim.

2させて頂く is humble and polite

お手伝いをさせて頂く literally frames the help as something she is allowed to do.

3The sentence trails off after なって

A fuller ending would be ことになっています or similar.

Vocabulary

研究室 (Laboratory)

研究室(けんきゅうしつ) means a laboratory, seminar room, or research office. In schools it often refers to a professor’s lab.

学生 (Student)

学生(がくせい) means a student, someone engaged in study at a school or university. It is the broad everyday word for a learner within an educational system.