A proton beam accelerated by the J-PARC main ring (MR) is slowly extracted by a third integer resonant extraction and delivered to the hadron experimental facility . A low beam loss (a high extraction efficiency) operation has been achieved by slow extraction schemes designed to reduce the machine damage and radiation exposure in the hands-on maintenance. A dynamic bump scheme is very effective to obtain the high extraction efficiency. The schemes and the slow extraction devices will be briefly introduced in this talk. Approaches to improve spill time structure under poor current ripples of the lattice bending and quadrupole magnets will be also shown. The slow extraction operation has restarted since April in this year after the radioactive material leak incident . Intensity dependent phenomena have been seen in the present operation. Plans to achieve a higher beam power and accelerator studies for the mu-e conversion experiment (COMET) will be also shown in this talk.