Supreme Magnet acquired.
「超級マグネット」を入手しました。
101Leafy researched the game with the Hilltop Works fan translation patch, English translation by Cargodin

Supreme Magnet is item 15 of the game's item table, in the Items group. The script names it on disc 1.
Lines of the script that name it, each with a link to its place in the script.
Supreme Magnet acquired.
「超級マグネット」を入手しました。
I found all of the keys! Now you can break the barrier!
Just be careful, because like I mentioned, the compass doll is surely possessed by malice.
That doll remembers the correct angles for the bagua mirrors.
To correct every mirror, we absolutely need that doll!
What can we use to... Oh! Wait! I have a supreme magnet!
鍵はみんな揃った。結界を解くことができるぞ。
ただ、メールに書いたとおり、コンパスドールは邪気にとり憑かれてしまっている。
ドールは八卦鏡の正しい角度を覚えている…
八卦鏡の角度を正すためにはどうしても必要だ。
これでなんとかなるか…超級マグネットだ。
Item table: Guilü Ball Supreme Magnet Keyhole Centre Key
English translations by Cargodin for Hilltop Works Fan Translation Patch: https://www.patreon.com/hilltopworks/posts/kowloons-gate-160555525?collection=18503