for connecting the IoT, has been launched globally [12]. Notably, the adoption of millimeter waves (mmWaves), which offer a broader bandwidth for enhanced throughput, marked the first in mobile communications to address the swiftly rising user traffic [13]. It is clear from this that, increasingly, the amount of data generated by mobile communications will further increase. In addition, Industry 5.0 has recently been envisioned by the European Commission as a roadmap for the future, aiming to foster a prosperous society through the strategic use of advanced technologies such as artificial intelligence, robotics, big data, and the IoT [14]. These technologies are being put to practical use in digital twins that connect the real and virtual worlds [15]. Unmanned Aerial Vehicles (UAVs), which can move freely in three dimensions, are essential to realizing Industry 5.0 [16; 17]. UAVs have recently been widely used in military and civilian applications, characterized by their high mobility, rapid deployment, and low cost. Examples of use include reconnaissance, transportation, inspection, agricultural irrigation, disaster relief, and many other fields [18; 19; 20; 21; 22]. While high-quality communications are available to everyone, there are situations in which communications become unavailable. This is the case during major disasters and large-scale events: the magnitude 6.5 Kumamoto earthquake in April 2016 caused landslides and commercial power outages that knocked out as many as 400 cell phone base stations (BSs), rendering cell phones temporarily unusable [23]. In addition to earthquakes, there have been many cases overseas where communications have been disrupted due to hardware damage caused by hurricanes [24; 25]. Since communication is necessary for rescue operations during a disaster, restoring the communication environment quickly is essential [26; 27; 28]. During large-scale events, the number of accesses and the amount of traffic in a local area will increase due to the active posting of videos and photos due to the spread of social networking services (SNSs), creating a situation where sufficient communication is impossible [29]. Adding more BSs to cope with these temporary situations is costly for installation and maintenance. In addition, since mobile base station vehicles are affected by the ground environment, such as going to the site to install them for communication area restoration, it is difficult to respond quickly in the event of road damage [30]. Therefore, a temporary network is needed that can provide high-capacity communications and flexibly change the location of its provision. Therefore, network construction using mmWave frequency band radio waves and UAV base stations is expected. We will use UAV BSs that utilize mmWave band radio waves to address these issues. mmWave radio waves are in the 30-300 GHz band, a high-frequency band characterized by high-capacity, low-latency communications [31]. In addition, drones are not dependent on the ground environment, such as traffic conditions, and can be deployed remotely and unmanned. The mmWave bandwidth has the disadvantages of being vulnerable to obstacles and being affected by distance attenuation [32]. UAV technology enables communications from the sky, which provides a clear line of sight, and beamforming technology enables high-quality communications. The system architecture of a mmWave UAV BS is shown in Figure 1[33]. Here, we consider a situation where the existing cellular communication network is no longer available. The entire system is divided into two parts: backhaul UAVs and access link UAVs. The backhaul UAVs connect the access link UAVs with available ground BSs far from the user. By deploying an appropriate location and number of backhaul UAVs, multi-hop communication is possible even when the distance between the user and the ground BS is large. Access link UAVs communicate directly with users instead of BSs. mmWave bands are used for all radio communications between these backhaul UAVs and the access link UAVs.