Even if a shareholder who has filed an action to enforce liability or a shareholder who has intervened in a suit relating to the action to enforce liability as a co-party ceases to be a shareholder during the pendency of relevant suit, that person may conduct the suit in the following cases:
責任追及等の訴えを提起した株主又は第八百四十九条第一項の規定により共同訴訟人として当該責任追及等の訴えに係る訴訟に参加した株主が当該訴訟の係属中に株主でなくなった場合であっても、次に掲げるときは、その者が、訴訟を追行することができる。
when that person acquires shares in the wholly owning parent company of the relevant stock company through a share exchange or share transfer by that stock company; or
when, through a merger in which the relevant stock company is the company that disappears, that person acquires shares in the stock company incorporated as a result of the merger or acquires shares in the stock company surviving the merger or in its wholly owning parent company.
The provisions of the preceding paragraph apply mutatis mutandis when, in the case set forth in item (i) of that paragraph (including the cases where it is applied mutatis mutandis pursuant to this paragraph or the following paragraph), the shareholder referred to in the preceding paragraph ceases to be a shareholder of shares in the wholly owning parent company of the relevant stock company during the pendency of the suit referred to in that paragraph. In these cases, the term "the relevant stock company" in that paragraph (including the cases where it is applied mutatis mutandis pursuant to this paragraph or the following paragraph) is deemed to be replaced with "the relevant wholly owning parent company".
The provisions of paragraph (1) apply mutatis mutandis when, in the case set forth in item (ii) of that paragraph (including the cases where it is applied mutatis mutandis pursuant to the preceding paragraph or this paragraph), the shareholder referred to in paragraph (1) ceases to be a shareholder of shares of the stock company that is incorporated in the merger or the stock company surviving a merger, or the wholly owning parent company thereof, during the pendency of the suit referred to in that paragraph. In these cases, the term "the relevant stock company" in that paragraph (including the cases where it is applied mutatis mutandis pursuant to the preceding paragraph and this paragraph) is deemed to be replaced with "the stock company that is incorporated in the merger or the stock company surviving a merger, or the wholly owning parent company thereof".
定義第二条第一項第三十一号・法令全体に適用
株式会社がその発行済株式（株式会社が発行している株式をいう。以下同じ。）の全部を他の株式会社又は合同会社に取得させること
略称規定第八百四十七条第一項・この節の中だけ
…第百二十条第三項の利益の返還を求める訴え又は第二百十三条の二第一項若しくは第二百八十六条の二第一項の規定による支払若しくは給付を求める訴え（以下この節において「責任追及等の訴え」という。）の提起を請求することができる。
わかりやすく言うと
発起人や取締役・監査役・清算人などの責任を追及する訴え、不公正な価額での引受けや払込みの仮装をした株式・新株予約権の引受人などに支払を求める訴え、違法な利益の供与の返還を求める訴えのことです。
定義第八百四十七条の二第一項・この節の中だけ
特定の株式会社の発行済株式の全部を有する株式会社その他これと同等のものとして法務省令で定める株式会社
わかりやすく言うと
ある株式会社の発行済株式の全部を持つ株式会社のことです。これと同等のものとして法務省令で定める株式会社も含みます。