Well, 秘密が漏れました (himitsu ga moremashita, the cat is out of the bag), 今年の漢字は... (kotoshi no kanji wa..., the kanji of the year is...) perhaps Tokyo Gov. Yuriko Koike can announce it, governor?「密です！」 (“Mitsu desu!,” “It’s mitsu!”)
Thank you, governor! Beating out other coronavirus-related contenders [see below], the kanji “密” (mitsu, dense/close) was seen mostly in the 3密 (sanmitsu) campaign used by Koike to prevent the spread of COVID-19: Avoid 密閉空間 (mippei kūkan, closed spaces), 密集場所 (mishū basho, crowded places) and 密接場面 (missetsu bamen, close-contact settings).
These three words all utilize 密’s meaning of being in close proximity without much space between objects or people. However, this character can also be used to express secrecy and keeping information away from others, which is why it is present in the words 秘密 (himitsu, secret), 機密 (kimitsu, confidentiality) and 密輸 (mitsuyu, smuggling).