first we've got official stuff, songs associated with him on the soundtracks and also his character songs:
trapped by the ocean scent - SDR2 soundtrack
abnormality on the girls front line - UDG soundtrack
poison -gekiyaku- - megumi ogata
I believe that hope / and will offer my pulsating heart / for the sake of that brilliance
zettai kibō birthday - megumi ogata
I keep waiting with bated breath for the very moment you wake up / in the muddy stream of red tears, being pushed and swallowed, sinking further down
zansakura -zanka- - megumi ogata
at the moment I realized, the withering branch had been left behind all alone / had been broken, still decaying, still keeping on yearning

and now the stuff I picked out:
blow my brains out - tikkle me
unlucky me, aware of the pain / all 'cause I happen to have some brain
millie, warm the kettle - rabbitology
millie, can't you stop them? you slow no omens / like exhaling it never ends
tongues and teeth - the crane wives
I will only break your pretty things / I will only wring you dry of everything
spiracle - flower face
and I want your violence, your silent sedation / your moon eyes, your telescope, morbid fixation
laplace's angel (hurt people? hurt people!) - will wood
the only ones in need of love are those who don't receive enough / so evil ones should get a little more
feel better - penelope scott
'cause someone loved me, someone fucking loved me / someone fucking loved me, I loved them too
teen idle - marina
and the day has come where I have died / only to find I've come alive
curses - the crane wives
ashes, ashes, dust to dust / tell me I am good enough
saint bernard - lincoln
I said make me love myself so that I might love you / don't make me a liar, 'cause I swear to god / when I said it I thought it was true