The first part of the joint doctoral school of the Faculty of Mathematics and Informatics (FMI) at Sofia University "St. Kliment Ohridski" and the University of Aizu, Japan, took place in the period 24-30 August 2025 in Sofia in the new research complex - the Center of Excellence "Universities for Science, Informatics and Technology in e-Society" (UNITe), located behind the building of the FMI, on the Lozenets campus. The joint doctoral school is held in two parts - the last week of August in Sofia and from 21 to 27 September at the University of Aizu (Fukushima, Japan).