Developing absolute asymmetric synthesis (AAS) to obtain optically active products from achiral starting materials without using any external chiral sources is very challenging. AAS can be achieved by designing a process in which a racemate is generated from the reaction of an achiral substrate and spontaneous mirror symmetry breaking (SMSB) involving dynamic preferential crystallization occurs. Successful examples of Michael addition, Strecker reaction, stereoisomerization, Diels-Alder reaction, aminal formation, acyloin condensation, photocycloaddition, aldol reaction, oxa-Michael addition, and desymmetrization have been reported so far. SMSB involving dynamic crystallization can be achieved by skillfully designing the conditions for a reaction via a reversible process or direct racemization of the products. The deracemization process can be accelerated by the Viedma ripening or temperature cycling methods, making it possible to develop asymmetric reactions on a large scale in a short time, and this is expected to be helpful as a practical organic synthesis method. In such reaction systems, it is possible to obtain high-purity optically active compounds from achiral substrates without using external sources of chirality such as chiral catalysts, and it has been suggested that this may be closely related to the mechanism of homochirality expression in the primitive Earth. Some of these reactions were featured in the 2020 edition of this series, and we will focus on successful examples developed by our group since then.