Somerville has worked as deputy manager on the £256m fund since September 2010, but has been with Jupiter since 2005 as joint head of the Far Eastern equities team. He previously worked for Cazenove as head of global and Japanese equities.
He will take over the running of the fund from 14 November, while Chatfeild-Roberts will become deputy manager.
The fund was launched in February and has been under Chatfeild-Roberts’ stewardship since 2001.
According to its latest factsheet, at the end of September it was down 5.6% over one year, compared to -4% for the benchmark and -4.9% for the sector average.
Over three years the fund has returned 15.5%, compared to benchmark returns of 17.8% and sector returns of 15.7% and for both periods it is ranked in the third quartile.
Since launch, however, the fund has achieved first quartile performance with returns of 146.5% over the period.
Jupiter said Chatfeild-Roberts would continue to provide input into the fund’s asset allocation strategy. His main focus will now be on his role as CIO of the group, which he has held since last year.
Somerville remain the lead manager of Jupiter’s Japan funds and will be supported in this role by Dan Carter who has been appointed deputy manager for both portfolios.
The £478m Jupiter Japan Income Fund has returned 18.6% since launch, according to Jupiter, compared to -1.2% for the IMA Japan sector average.
Meanwhile the £51m Jupiter Japan Select Fund, which is a Sicav, has returned 12.5% compared with 7.9% for the FO Equity Japan sector average since launch in July 2009.
Chatfeild-Roberts said: "With my role having expanded since I became CIO last year I feel the time is right to hand over full-time responsibility for this portfolio to Simon. It is also pleasing to be able to appoint Dan as deputy manager on both our Japan funds. He has worked hard and deserves greater responsibility."
