School Trilogy is the first Korean-language and Japanese-language era of BTS's career. It started on June 12, 2013 with their Korean debut single album 2 Cool 4 Skool and officially finished on November 20, 2014 with "Danger (Mo-Blue-Mix) (Feat. Thanh)" music video. Meanwhile in Japanese-language, starting on May 23, 2014 with their first Japanese compilation album 2 COOL 4 SKOOL / O!RUL8,2? and officially finished on December 24, 2014 with their first Japanese studio album Wake Up. All the content released in this era have the concept of "a defiant teenager".
This era is the first part of BTS Chronicle, Reflection of Youth and isn't officially connected with the fictional BTS Universe.
All the Korean-language and Japanese-language content released in this era have the concept of "a defiant teenager"  as both have the same songs only in different languages.
- 2 Cool 4 Skool: It is the debut album of BTS.
- O!RUL8,2?: It is first BTS's mini album, and contains the message of finding one's happiness before it is the too late.
- Skool Luv Affair: It is second BTS's mini album and the title song "Boy In Luv," is about a school bad boy who falls in love with a girl.
- Dark & Wild: It is first BTS's studio album and the meant is to be a direct continuation of the theme in their previous release, the title song "Danger" is about a man who has started dating but isn’t receiving equal attention from the girl he loves. 
- 2 Cool 4 Skool / O!RUL8,2?: This is BTS's first Japanese compilation album
- "No More Dream": This is BTS's debut Japanese single.
- "Boy In Luv": This is BTS's second Japanese single.
- "Danger": This is BTS's third Japanese single.
- Wake Up (album): This is BTS's debut Japanese album containing all previously released singles.
List of content released in this series.
|2 Cool 4 Skool||Single album||June 12, 2013|
|'No More Dream' Official MV||Music video||June 12, 2013|
|'No More Dream' Official MV (Choreography Version)||Music video||June 17, 2013|
|'We Are Bulletproof Pt.2' Official MV||Music video||July 16, 2013|
|O!RUL8,2? Comeback Trailer||Comeback trailer||September 5, 2013|
|O!RUL8,2?||Mini album||September 11, 2013|
|'N.O' Official MV||Music video||September 11, 2013|
|Skool Luv Affair 'Skool Luv Affair' Comeback Trailer||Comeback trailer||February 2, 2014|
|Skool Luv Affair||Mini album||February 12, 2014|
|'상남자 (Boy In Luv)' Official MV||Music video||February 12, 2014|
|'상남자 (Boy In Luv)' Official MV (Choreography Version)||Music video||February 20, 2014|
|'하루만 (Just One Day)' Official MV||Music video||April 6, 2014|
|Skool Luv Affair Special Addition||Repackage album||May 14, 2014|
|DARK & WILD 'What Am I To You' Comeback Trailer||Comeback trailer||August 5, 2014|
|DARK & WILD||Studio album||August 19, 2014|
|'Danger' Official MV||Music video||August 19, 2014|
|'호르몬전쟁' Official MV||Music video||October 21, 2014|
|"Danger (Mo-Blue-Mix) (Feat. Thanh)"||Digital single||November 20, 2014|
|'Danger (Mo-Blue-Mix) (Feat. Thanh)' MV||Music video||November 20, 2014|
|'NO MORE DREAM -Japanese Ver.-' Official MV||Music video||May 25, 2014|
|"NO MORE DREAM -Japanese Ver.-"||Japanese single||June 4, 2014|
|'BOY IN LUV -Japanese Ver.-' Official MV||Music video||July 4, 2014|
|"BOY IN LUV -Japanese Ver.-"||Japanese single||July 16, 2014|
|'Danger -Japanese Ver.-' Official MV||Music video||November 9, 2014|
|"DANGER -Japanese Ver.-"||Japanese single||November 19, 2014|
|Wake Up||Studio album||December 24, 2014|
List of events promoting the releases from this era.
- BTS Live Trilogy Episode II: The Red Bullet (October 17, 2014–August 29, 2015)
- BTS's First Japan Tour-Wake Up: Open Your Eyes (February 10–19, 2015)
- BTS Live Trilogy Episode I: BTS Begins (March 28–29, 2015)