Editing Chain letter (section)

==Relationship to Urban Legends==
Chain letters often function as vectors for [[urban legend]]s. The structure "learn this story/break this rule, suffer misfortune unless you pass it on to X people within Y time" is common to both.

In Japan, specific urban legends are thought to be influenced by or derived from Fukou no Tegami:
*   '''[[Kashima Reiko|Kashima-san (カシマさん)]]:''' A legend popular around 1972 involving a vengeful female ghost (often legless). Hearing the story invites her appearance, but telling it to a certain number of people within a set time (e.g., 3 days) transfers the curse.<ref name="日本現代怪異事典_p89"/><ref name="日本現代怪異事典_p91"/><ref name="カシマさんを追う_p170"/> Early media reports explicitly compared Kashima-san to "Lucky Letters" (likely meaning the Fukou no Tegami type prevalent then), calling it a "word-of-mouth version".<ref name="実話ナックルズ20231228_p55"/><ref name="カシマさんを追う_p208"/><ref name="平凡パンチ9(34)_p56"/><ref name="謎解き都市伝説_p201"/><ref name="カシマさんを追う_p169"/><ref name="朝日新聞19721011m_p17"/> Some researchers propose Kashima-san originated as a narrative justification for the misfortune threatened by Fukou no Tegami, which then detached from the physical letter format as it spread orally.<ref name="カシマさんを追う_p174"/><ref name="実話ナックルズ20231228_p55"/>
*   '''[[Sacchan (urban legend)|Sacchan (サッちゃん)]]:''' A late 1990s chain mail legend claiming the popular children's song "[[Sacchan (song)|Sacchan]]" has a hidden fourth verse revealing the titular girl died in a train accident in Hokkaido.<ref name="カシマさんを追う_p190"/> Learning this verse supposedly brings a curse, avoidable only by telling five people within three hours.<ref name="新潮44(34)_p145"/><ref name="日本現代怪異事典_p171"/> (The song's actual lyricist denied this backstory).<ref name="毎日新聞20061013e_p15"/><ref name="カシマさんを追う_p191"/><ref name="カシマさんを追う_p192"/>

The structural similarity—a contagious curse requiring propagation for the host's salvation—strongly suggests these legends adapted the chain letter mechanism.<ref name="現代20220109_p2"/><ref name="日本現代怪異事典_p329"/>