Arranged to assist in a lab with 〜ことになる

Grammar Explanation: To end up being with 〜ことになる

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

3The sentence trails off after なって

A fuller version would be ことになりまして, the polite て-form, with “so I’m here” left unsaid.

学生 (Student): 学生(がくせい) means a student, especially at a school or university.
理学部 (Faculty of Science): 理学部(りがくぶ) is the university faculty of natural sciences, such as physics, chemistry, and biology.
こちら (This way): こちら is a polite word for “here”, “this way”, or “this one”. It can also politely mean “I” or “we”.
研究室 (Laboratory): 研究室(けんきゅうしつ) means a laboratory or research office. At a university, it often means a professor’s lab.
させる (To make someone do): させる is the causative form of する. It means to make someone do something or to let them do it.
頂く (To receive): 頂(いただ)く is a humble way to say you receive something. After させて, it politely asks or announces that one will do something.
こと (Thing): こと is an abstract thing, matter, or fact, as opposed to a physical object. It also turns a verb phrase into a noun, as in 見たことがある. It is also written 事(こと).
なる (To become): なる is to change into a different state or become something. It also means something turns out a certain way. It is also written 成(な)る.