Electric Lady Studios, in Greenwich Village, is a working music museum. The Fender Twin amplifier that the studio’s onetime owner Jimi Hendrix brought to work before his 1970 death remains, as does an electric piano Stevie Wonder used on an astounding run of records. There’s a keyboard Bob Dylan played in Muscle Shoals and several lurid murals by the painter Lance Jost, originals depicting interstellar travel and Aquarian-age sexual exploration.

But Lee Foster — the former intern who became the space’s co-owner in 2010, after helping rescue it from financial ruin — keeps his drawings by the singer-songwriter Daniel Johnston in a small safe in the corner of his office, each page bound in plastic in a lime-green three-ring binder.

“It has nothing to do with financial value,” Foster said in his art-lined room last month, as afternoon slipped into evening. “It is so meaningful that, even if it was for that hour or three when he was sitting down to draw, it was all he was thinking about. There’s a little bit of his soul in there.”

Soon after Johnston’s death in 2019, at 58, Foster became the unexpected custodian of Johnston’s unexpectedly enormous art archive. His career hamstrung by bipolar disorder and stints in psychiatric hospitals, Johnston first found acclaim as an unguarded and guileless songwriter in the late ’80s with tunes that cut instantly to the emotional quick.

But he drew obsessively for more than half a century, too, creating a cosmos of characters — affable ghosts, flying eyeballs, his famously friendly frog, Jeremiah — that revealed his insecurities and hopes, sexual frustrations and religious aspirations. Foster estimates there may be 15,000 such pieces, many never seen beyond Johnston’s family. “Daniel Johnston: I’m Afraid of What I Might Draw,” a book released in late April, is the first authoritative collection of Johnston’s art and a revelation about how he experienced the world.

“He was not drawing these things to entertain us. He was drawing to entertain himself,” Dick Johnston, his older brother, said in a video interview from his home in Katy, Texas, frames and figurines of Daniel’s art lining his bookshelves. “He was real and earnest, and these are his moments in time. You get what an experience was for him.”

Foster, 47, first learned of Johnston when Kurt Cobain began sporting a white T-shirt printed with the cover of his 1983 tape “Hi, How Are You: The Unfinished Album.” He read about him in music magazines, too. Raised in rural Tennessee, however, Foster didn’t have easy access to Johnston’s records. The 2005 documentary “The Devil and Daniel Johnston” — so candid about Johnston’s struggles with mental illness and medication, plus assorted escapades with the circus and Sonic Youth — rekindled his interest. “As a kid, one of my favorite things was ‘Pee-Wee’s Big Adventure,’ and I always made that comparison,” Foster said. “His life was stranger than fiction.”

In the summer of 2019, Foster saw a Johnston drawing framed on a singer-songwriter’s studio wall. He wondered how he might get one himself. (The reply — “I send his family money all the time” — wasn’t particularly helpful.) He found an illustration of a Kung Fu-trained Captain America on eBay for $900, then asked Johnston’s family if he could visit and browse Johnston’s other work. He arrived in November, two months after Johnston died and just after the family sold $500,000 of merch in mere weeks. Dick revealed box after box of drawings, and they waded through them together late into the night.

“After a while, you handle these pages, and they’re just pages,” said Dick, 71. He began helping to manage his brother’s career full-time in 2001 and became his guardian in 2012. “But Lee was someone who could say, ‘No, no, look at this one.’ It had been a while since I had done that. It was a giddy sharing.”

Foster recognized that, grief notwithstanding, Dick was now responsible for an overwhelming amount of material — 150 journals, thousands of hours of recorded songs and conversations, all those drawings. Dick has now digitized two-thirds of those tapes and is adding appropriate excerpts from them to reissues of his brother’s albums. (“If we write a script for a movie,” he said, “it’s like he’s already written it for us.”) The rest reminded Foster of when he was faced with saving Electric Lady, with preserving an overwhelming legacy. He offered to help, first by delivering drawings Johnston had done of musicians like Cat Power and Elvis Costello to their subjects.

He steadily became so obsessed with seeing and understanding all the work that, days before his 2024 wedding, he surrounded himself in Electric Lady’s Studio A with Johnston’s drawings, trying to tease out a page order for “I’m Afraid of What I Might Draw.” He sent Dick a video. “I said, ‘Don’t you have something else you need to be doing, son?’” Dick said, laughing. “Man, he was committed.”

In song, Johnston had an uncanny ability to capture complicated feelings with a few incisive lines, bleated sweetly over chords pounded or strummed. If “Mind Movies” captures being forever uneasy with your own thoughts, “True Love Will Find You in the End” is a bittersweet hymn about the pain of perseverance. He did the same with pen and paper. Surrounded by jeering demons, he appears catatonic in the sketch “Alone Again Naturely.” Elsewhere, Satan looks up from a busty doodle, a Johnston favorite, to declare “I Think I Draw I Am,” a wry moment of self-censure.

In conversation, both Foster and Dick eventually discuss the same drawing, which now lives inside the safe at Electric Lady. Standing in a field of stumps as a half-dozen bats swoop in overhead, Johnston points toward a single sprout and grins. “There is still hope!” he says.

“Isn’t life a disaster and a train wreck? And here I am, and I climb out of it,” Dick said. “You don’t always know what your inner self is, but it reveals itself in your choices. Dan would hang onto that hope.”