Two concurrent exhibitions of Takashi Murakami's works – a major solo exhibition at the Mori Art Museum and a 'pop-up' of 15 new paintings from his 'Ensō' series at his own Tokyo gallery – offer an intriguing perspective on the contemporary artist's renewed focus on traditional Japanese art.

Although widely exhibited outside of his home country, the Mori Art Museum's exhibition of 50 works including paintings, sculptures and videos is the first significant show of his work in Japan since 2001.

The undisputed highlight is an extraordinarily detailed and colourful 100-metre-long painting that depicts the Buddha's disciples transformed into a mesmerising riot of bulging eyes and toothless grins amid a psychedelic landscape. Titled The 500 Arhats, it was inspired by a set of 100 hanging scrolls created by Kanō Kazunobu (1816–1863).

They are 'unadorned self-portraits of Murakami himself', observes the exhibition's curatorial advisor, art historian Tsuji Nobuo.

Also on show are Murakami's working instructions and sketches used by 200 students from Japanese art colleges who helped complete the work following the 2011 earthquake and tsunami in Japan. Murakami says the disaster had a 'profound influence' on the new direction of his work although his trademark controversial commentary on the complex political and social issues facing modern Japan remains a key theme. For instance, the enormous gold-leaf-clad sculpture The Birth Cry of a Universe represents contemporary society collapsing under the weight of the pursuit of development.

Meanwhile, at his own gallery, a decidedly more minimalist, contemplative series of paintings feature the Ensō or 'circle', a motif in Japanese Zen Buddhism symbolising emptiness, unity and infinity. Here, Murakami – who has a PhD in Nihongo painting – reinterprets the traditional fluid brush stroke, using spray paint over a background of smiling flowers and skulls. He says this new style emerged after he sprayed the word 'HOLLOW' as graffiti on a completed painting.

The artist may be engaged in complex spiritual themes but he has not lost his maverick sense of humour. When asked why his Ensō paintings are in contrasting combinations of black, white, gold and red, he joked, 'Because I thought someone might want to buy them in different colours.'