Ask Mitski Miyawaki about happiness and she'll warn you: "Happiness fucks you." It's a lesson that's been writ large into the New Yorker's gritty, outsider-indie for years, but never so powerfully as on her newest album, 'Puberty 2'. "Happiness is up, sadness is down, but one's almost more destructive than the other," she says. "When you realise you can't have one without the other, it's possible to spend periods of happiness just waiting for that other wave." On 'Puberty 2', that tension is palpable: a both beautiful and brutal romantic hinterland, in which one of America's new voices hits a brave new stride.The follow-up to 2014's 'Bury Me At Makeout Creek', named after a Simpsons quote and hailed by Pitchfork as "a complex 10-song story [containing] some of the most nuanced, complex and articulate music that's come from the indiesphere in a while," 'Puberty 2' picks up where its predecessor left off. "It's kind of a two parter," explains Mitski. "It's similar in sound, but a direct growth [from] that record." Musically, there are subtle evolutions: electronic drum machines pulse throughout beneath Pixies-ish guitars, while saxophone lights up its opening track. "I had a certain confidence this time. I knew what I wanted, knew what I was doing and wasn't afraid to do things that some people may not like." In terms of message though, the 25-year-old cuts the same defiant, feminist figure on 'Puberty 2' that won her acclaim last time around (her hero is MIA, for her politics as much as her music). Born in Japan, Mitski grew up surrounded by her father's Smithsonian folk recordings and mother's 1970s Japanese pop CDs in a family that moved frequently: she spent stints in the Democratic Republic of Congo, Malaysia, China and Turkey among other countries before coming to New York to study composition at SUNY Purchase. She reflects now on feeling "half Japanese, half American but not fully either" – a feeling she confronts on the clever 'Your Best American Girl' – a super-sized punk-rock hit she "hammed up the tropes" on to deconstruct and poke fun at that genre's surplus of white males. "I wanted to use those white-American-guy stereotypes as a Japanese girl who can't fit in, who can never be an American girl," she explains.Elsewhere on the record there's 'Crack Baby', a song which doesn't pull on your heartstrings so much as swing from them like monkey bars, which Mitski wrote the skeleton of as a teenager. As you might have guessed from the album's title, that adolescent period is a time of her life she doesn't feel she's entirely left behind. "It came up as a joke and I became attached to it. 'Puberty 2'! It sounds like a blockbuster movie" – a nod to the horror-movie terror of adolescence. "I actually had a ridiculously long argument whether it should be the number 2, or a Roman numeral."The album was put together with the help of long-term accomplice Patrick Hyland, with every instrument on record played between the two of them. "You know the Drake song 'No New Friends'? It's like that. The more I do this, the more I close-mindedly stick to the people I know," she explains. "I think that focus made it my most mature record."Sadness is awful and happiness is exhausting in the world of Mitski. The effect of 'Puberty 2', however, is a stark opposite: invigorating, inspiring and beautiful.