JAPANESE CIVIL CODE OF 1896

Based on the English Translation by: J. E. de Becker (1909 – 1910). Annotated Civil Code of Japan. London: Butterworth & Co. [Available on Google Books and Archive.org: Volume 1, Volume 2, Volume 3, Volume 4]
"INDEX TO ARTICLES" in his another work offers additional information: J. E. de Becker (1921). The Principles and Practice of Civil Code of Japan. London: Butterworth & Co. [Available on Archive.org]

BOOK III. OBLIGATIONS (or CLAIMS).

[I] An offer of a contract made with a fixed period of time specified for acceptance cannot be withdrawn.
[II] When the offerer has received no notice of acceptance within the period of time of the preceding Paragraph, the offer loses its effect.

《References by de Becker》

(In reference vide Art. 97, Paragraph 1, and Art. 526; also Arts. 145, 146 and 148 of the German Civil Code.)

[I] Even when the notice of acceptance has reached the offerer subsequent to the period of time mentioned in the preceding Article, if it can be recognised that it was despatched at such a time that under ordinary circumstances it ought to have arrived within the period of time, the offerer must without delay give notice to the other party of the delayed arrival; but this does not apply when a notice of delay has been already despatched previous to arrival.
[II] When the offerer has neglected to give the notice of the preceding Paragraph, the notice of acceptance is regarded as not having been delayed.

《References by de Becker》

(In reference vide Art. 521, Paragraph 2; also Art. 149 of the German Civil Code.)