UAE's space policy is interesting. Since they are a nascent player in the space industry, they have decided on acquiring knowledge through economic and scientific collaboration. Towards this goal, they don't mind working with foreign private players or government space agencies.
In contrast to the autarkic path followed by other nations, and in accordance with the recommendations of their engineers and scientists, the Emirati authorities have decided to reach the moon in the easiest and quickest way possible. To achieve this, they will use an American launcher and a Japanese commercial spacecraft already available ... They are investing huge resources to reorient the country from an economy based on oil extraction to a more technologically advanced goal. They want Emirates to be a preferred partner of space agencies from the United States, Russia, China, India, Japan and Europe in preparing for future manned missions to the surface of Mars from the Moon. - Emirates is partnering with a private company from Japan to touch down on the moon in 2022
It however doesn't mean that they are just throwing their oil money and buying technology from anyone who offers.
Progressing from Earth-orbiting satellites to a deep-space mission in six years is “incredible”, says Brett Landin, an engineer at the University of Colorado Boulder, who leads the mission’s spacecraft team. The UAE hired the US engineer in an unusual partnership in which the Colorado team provided both mentoring and construction expertise. “I’ve never seen anything like this before,” says Landin.
... Sharaf, then one of the country’s few satellite engineers, got a call directly from the UAE’s vice-president and prime minister, Mohammed Bin Rashid Al Maktoum, asking if the country could go to Mars by 2021 ... A Mars mission is many times more complex than parking a satellite into a low-Earth orbit, Al Amiri says, and historically around half of the trips to the red planet have failed ... To do it, the country tapped into foreign expertise, using a model that had shown success before. In 2007, the UAE had hired South Korean firm Satrec Initiative to design and build its first satellites, with the understanding that the company would also train Emirati engineers. By 2018, the UAE was able to launch a satellite designed and built entirely at home.
Applying the same process to the Mars mission, the UAE hired old hands from NASA missions, mainly at the University of Colorado Boulder, to work alongside them and provide training in how to send a probe to another planet ... Sharaf was told by his superiors to “build it, not buy it”, to create skills within the UAE itself. So under Sharaf’s leadership, US and Emirati engineers worked together on every part of the mission’s development, from design to manufacture, with work taking place largely in Boulder, but also at the MBRSC.
For its science goals, the UAE went to the Mars Exploration Program Analysis Group, a NASA-led international forum that agrees on gaps in knowledge to tackle in future Mars missions. - How a small Arab nation built a Mars mission from scratch in six years
According to UAE's GulfNews, the Mars mission "involved collaboration with scientists and engineers from several countries, including the United States, Japan, and the United Kingdom." Their Lunar mission is another international collaboration that aimed to launch a rover to the moon, with a moon lander designed by a Japanese startup, Ispace, and launched from the Kennedy Space Center in Florida on an American SpaceX Falcon 9 rocket.
So it is not as if the UAE is bound to the Japanese with some exclusive agreement - the available public information highlights that the UAE is working with everyone in the west, and it's allies, South Korea and Japan in Asia.
But note that Japan has also recently revived its Space program and has ambitious goals. The Japanese have also been seeking investments from UAE (the UAE has a huge sovereign fund). Thus, it is likely that Japan offers the UAE better terms when collaborating with them on their space programs and thus there are more avenues for closer collaboration between the two countries.
Japan has contributed to the UAE's space policy for many years. The launch of the UAE's first domestically-manufactured satellite KhalifaSat in 2018 and the Mars Exploration Hope Probe in 2020 were both carried out by Japanese H2-A rockets. The launch of the UAE’s lunar probe Rashid Rover this April, operated in collaboration with Mohammed Bin Rashid Space Center (MBRSC) and Japanese space startup company, ispace, was a significant step forward as the world’s first attempt by a private company to land a moon-surface rover. I am confident that future-oriented efforts such as this will lead to a greater success in the near future. Japan is determined to continue its support for further collaboration in the space field. - Towards the Next 50 Years between Japan and UAE.
The Russians have a slightly different perspective on this though.
They believe that the US is working behind the scene to foster these collaborations with UAE, so that the US can lock it down with western technologies and also try to upgrade its relationships with UAE in the middle-east to the level that it has with South Korea and Japan in Asia. This can, in the long-term, counter the influence of the Chinese and the Russians in the Middle East.
The director general of the Russian Space Agency (Roscosmos), General Yuri Borisov, has just concluded his three-day tour of the United Arab Emirates. He came to the Gulf country with a large representation of senior Kremlin space officials in order to rebalance as far as possible the considerable influence that Washington exerts over Emirati organisations and the growing Emirati industrial fabric. - Russia seeks closer space cooperation with Emirates to rebalance US influence