Outside Asia, many people have never heard the name Kannon. If you're interested in Buddhism, you may know the Sanskrit name Avalokiteśvara or the Chinese form Guanyin. In Japan, though, you meet Kannon everywhere, in cemeteries, in temples, on mountaintops and by the roadside. Kannon is the bodhisattva who never stops listening, and who answers whoever calls.
In Shingon, Kannon has a special place, and for Reiki there's a very concrete connection, which I'll come to below.
The name 観音
The longer form of the name is Kanzeon 観世音, "the one who perceives the sounds of the world." The Lotus Sutra describes how Kannon hears all calls, everywhere and at the same time. You could say this isn't a superhuman ability but the natural expression of boundless compassion. Kannon listens because Kannon can't do otherwise.
In India, Avalokiteśvara was depicted as male. In China and Japan the depiction changed over time, and today Kannon appears in many forms, sometimes androgynous, sometimes with female features, sometimes with eleven heads or a thousand arms. The form changes, and the compassion remains.
Kannon in Shingon 真言
In Shingon, compassion (jihi 慈悲) isn't one quality among many. Kūkai's great source, the Mahāvairocana Sutra, says that awakening has the mind of awakening as its cause, great compassion as its root and skillful means as its culmination. Kannon embodies exactly this great compassion.
The lotus is Kannon's symbol. In Shingon, the whole group of beings around Kannon is called the lotus family (renge-bu 蓮華部). The lotus grows out of the mud and yet blossoms pure, and that's how Shingon sees the pure heart in every being. In the Ajikan meditation, the eight-petaled lotus of the heart is contemplated, so in a sense you meet Kannon within yourself there.
The forms of Kannon 変化
Kannon takes on whatever form a suffering being needs. In Japan there's the group of the Six Kannon (roku Kannon), one for each of the six realms of existence. Four of them are especially well known.
Senju Kannon
千手観音A thousand hands with an eye in each palm, in full Senju Sengen Kanjizai Bosatsu (千手千眼観自在菩薩), "thousand hands, thousand eyes." The eyes perceive the suffering of beings, and most of the hands also hold a tool. All those tools stand for the many different ways to help. In statues the thousand hands are usually represented by forty-two arms. Besides the two main hands in front of the chest, each of the other 40 saves the beings of 25 worlds, and 40 times 25 makes a thousand. At Sanjūsangen-dō in Kyoto there are 1,001 statues of Senju Kannon side by side.
Jūichimen Kannon
十一面観音Eleven faces: three compassionate, three wrathful, three with protruding fangs, one laughing and one Buddha face on top. They look in all directions, so that no one is overlooked.
Nyoirin Kannon
如意輪観音Kannon with the wish-fulfilling jewel (nyoi) and the wheel of the Dharma (rin). Six arms, seated in contemplation, with the cheek resting on one hand, as if thinking about your request right now.
Shō Kannon
聖観音The basic form, with two arms and a lotus. No extra arms and no eleven heads, simply compassion, clear and still.
The horse-headed Batō Kannon, the protector of animals, is also one of the Six Kannon.

Kannon in the mandala 曼荼羅
In the Womb Realm mandala (Taizōkai 胎蔵界曼荼羅), Kannon has a section of its own, the Kannon court (Kannon-in 観音院), also called the lotus court, right next to the central court with Dainichi Nyorai. Its position already says a lot. Compassion isn't a side issue, it sits right beside the center.
The mantra and the seed syllable 真言
In Shingon, a well known mantra of Kannon is the mantra of Senju Kannon, On bazara tarama kiriku. Kiriku is the Japanese pronunciation of the Siddham seed syllable (Siddham is called Bonji in Japanese) hrīḥ. Many people outside Japan know the mantra Oṃ maṇi padme hūṃ, which also refers to Avalokiteśvara. It comes mainly from the Tibetan tradition and plays only a small role in Japanese Shingon.
Kannon and Reiki 靈氣
And this brings us to the connection with Reiki. The second Reiki symbol, Sei He Ki, goes back to exactly this Siddham syllable hrīḥ, which stands for Senju Kannon and Amida Nyorai. I explain this in detail in the article on Sei He Ki. In the Shingon Reiki Master Path, Senju Kannon is also one of the initiations.
There's also a connection in practice. When you give Reiki, you listen, not with your ears but with your hands and your whole body. The hands notice where energy is stuck or where something wants to flow. This kind of bodily listening is exactly what Kannon's name describes, perceiving the sounds. Put simply, giving Reiki with compassion is in a way Kannon practice.

The 33 temples 巡礼
In Japan there are several Kannon pilgrimages. The best known is the Saigoku sanjūsansho 西国三十三所, the pilgrimage to 33 Kannon temples in western Japan. The number 33 comes from the Lotus Sutra, according to which Kannon can appear in 33 different forms. In each of these temples a different form of Kannon is honored, Senju Kannon in one, Jūichimen Kannon or Nyoirin Kannon in another. The diversity tells a single story, that compassion adapts to whoever needs it. On our spiritual journeys to Japan, Kannon is never far away, because you'll find Kannon in almost every temple.
Migawari Kannon 身代
One of the most touching forms of Kannon in Japan is Migawari Kannon 身代わり観音, "the Kannon who takes your place." Legends all over Japan tell of Kannon stepping in for a person in danger, and afterward the statue in the temple shows the wound or the burn mark that the person was spared. I find these stories beautiful, because they express in a very simple way something that Shingon describes in philosophical terms, that Kannon isn't far away. Which form of Kannon appeals to you most?
Meet the tradition
Kannon is very present in Shingon Reiki. If you like, have a look at how you can meet this tradition, in practice or on a journey to Japan.
Your path in Shingon Reiki Dainichi Nyorai