{{#^CD^# Infobox
|#^infoboxcolor1^#     = Smile
|#^infoboxname^#      = Otona ni Narutte Muzukashii<nowiki>!!!</nowiki>
|#^infoboxJapanese^#   = オトナになるって難しい!!!
|#^infoboxCover^#       = OtonaniNarutteMuzukashii-r.jpg
|#^infoboxCaption^#    = 
|#^infoboxCover^#2      = OtonaniNarutteMuzukashii-dvd.jpg
|#^infoboxCaption^#2   = #^SingleV^#
|#^infoboxtype^#        = #^Single^#
|#^infoboxartist^#     = [[S/mileage]]
|#^infoboxalbum^#      = [[Warugaki ①]]
|#^infoboxreleased^#     = 14 #^March^# 2010<br>3 #^April^# 2010 <small>(#^SingleV^#)</small>
|#^infoboxgenre^#       = J-Pop
|#^infoboxformat^#     = #^CD^# #^Single^#, #^SingleV^#
|#^infoboxlength^#      = 6:08
|#^infoboxlabel^# = {{LinkBug|UP-FRONT WORKS}}
|#^infoboxproducer^#  = [[Tsunku]]
|#^infoboxLast^#     = [[Suki-chan]] <small>3#^Ordinalth^# #^IndieSingle^# (2009)</small>
|#^infoboxNext^#      = [[Yumemiru Fifteen]] <small>1#^Ordinalth^# #^MajorSingle^# (2010)</small>
}}
'''Otona ni Narutte Muzukashii!!!''' (オトナになるって難しい!!!) 4#^Ordinalth^# #^IndieSingle^# [[S/mileage]].

==#^Tracklist^#==
[[#^File^#:Smileage - Otona ni Narutte Muzukashii!!! (MV)|thumb|right|220 px|S/mileage - Otona ni Narutte Muzukashii!!! (MV)]]
===#^CD^#===
#Otona ni Narutte Muzukashii!!!
#Otona ni Narutte Muzukashii!!! (Instrumental)
===#^SingleV^#===
#Otona ni Narutte Muzukashii!!! (MUSIC CLIP)
#Making Eizou (メイキング映像)

==#^FeaturedMembers^#==
*[[Wada Ayaka]]
*[[Maeda Yuuka]]
*[[Fukuda Kanon]]
*[[Ogawa Saki]]

==#^ConcertPerformances^#==
;Otona ni Narutte Muzukashii!!!
*[[Hello! Project 2010 Winter Kachou Fuugetsu ~Mobekimasu!~]]
*[[2010nen Hello Pro Egg Norimen Live 2gatsu]]
*[[Special Joint 2010 Haru ~Kansha Mankai! Mano Erina 2 Shuunen Totsunyuu & S/mileage Major Debut e Sakura Sake! Live~]]
*[[Hello! Project 2010 Summer ~Fankora!~]]
*[[S/mileage 1st Live Tour 2010 Aki ~Devil Smile Angel Smile~]]
*[[℃-ute & S/mileage Premium Live 2011 Haru ~℃ & S Collaboration Daisakusen~]] <small>- [[Suzuki Airi]], [[Okai Chisato]], Wada Ayaka, Maeda Yuuka</small>
*[[S/mileage 2011 Limited Live "S/mile Factory"]]
*[[S/mileage Concert Tour 2011 Aki ~Gyakushuu no Mini Skirt~]]

==#^SingleInformation^#==
*#^CreditsLyrics^#, #^CreditsComposition^#, #^CreditsChorus^#: [[Tsunku]]
*#^CreditsArrangement^#, #^CreditsProgramming^#, #^CreditsGuitar^#: [[Itagaki Yusuke]]

==#^OriconChartPositions^#==
{{OriconStart}}
{{OriconWeek|13,-,30,-,-,-,-,42/1324}}
{{OriconWeekOnly|162/342}}
{{OriconWeek|10,-,-,-,-,-,-,82/624}}
{{OriconFinish}}

'''#^OriconTotal^#:''' 2,290#^OriconTotalPost^#

==#^AdditionalVideos^#==
<gallery>
Smileage - Otona ni Narutte Muzukashii!!! (MV) (Dance Shot Ver.)|Dance Shot Ver.
Smileage - Otona ni Narutte Muzukashii!!! (MV) (Close-up Ver.)|Close-up Ver.
</gallery>

==#^ExternalLinks^#==
*#^Discography^#:
**#^Single^#: [http://wayback.archive.org/web/20140830000000/http://s-mileage.jp/discography/detail_00014/ S/mileage (#^archived^#)], [http://www.helloproject.com/release/detail/TGCS-6045/ Hello! Project], [http://wayback.archive.org/web/20141207000000/http://www.up-front-works.jp/discography/upfront/15/s_01/index.html UP-FRONT WORKS (#^archived^#)], [http://www.tsunku.net/producework.php?Music_ArtistID=130&@DB_ID@=473#01 Tsunku.net]
**#^SingleV^#: [http://wayback.archive.org/web/20140830000000/http://s-mileage.jp/discography/detail_00018/ S/mileage (#^archived^#)], [http://www.helloproject.com/release/detail/TGBS-4984/ Hello! Project], [http://wayback.archive.org/web/20141207000000/http://www.up-front-works.jp/discography/upfront/15/v_01/index.html UP-FRONT WORKS (#^archived^#)]
*#^Wikipedia^#: [http://ja.wikipedia.org/wiki/オトナになるって難しい!!! #^Japanese^#]
*#^LinkLyrics^#: [http://projecthello.com/smileage/otona.html Otona ni Narutte Muzukashii!!!]
{{S/mileage}}

[[en:Otona ni Narutte Muzukashii!!!]]
[[ja:オトナになるって難しい!!!]]
[[#^Category^#:#^CatGroupSinglePre^#ANGERME#^CatGroupSinglePost^#]]
[[#^Category^#:#^CatGroupDVDPre^#ANGERME#^CatGroupDVDPost^#]]
[[#^Category^#:#^CatYearSinglePre^#2010#^CatYearSinglePost^#]]
[[#^Category^#:#^CatYearDVDPre^#2010#^CatYearDVDPost^#]]
[[#^Category^#:#^CatMembersLineupPre^#4#^CatMembersLineupPost^#]]
[[#^Category^#:#^CatIndieSingles^#]]